Swimming Underground in Phong Nha
Published Sunday, April 27, 2025
Friday, April 4th - Bus to Ninh Binh
To get from Cat Ba Town to Ninh Binh, we book a standard tourist bus, this time it drives onto the ferry to the mainland, so we don't have to get off and get on another bus. The ride takes about four hours, getting us there a bit before midnight. We start to book a Grab, although there is already a taxi driver at the bus station asking if we want a ride. We show him the Grab price and ask if he'll take us for that price, and he agrees with an additional 50k VND (~2 USD) "exit fee" which seems fair for the midnight conveinence. We arrive at Sparrow Song Homestay ouside the Tam Coc neighborhood, check into our room, and go to sleep.
Saturday, April 5th - A not-so-restful rest day
This place ends up being okay. We felt mildly under attack from mosquitos throughout the night, and when we woke up we understood why as we opened the window to see the large pool of standing water directly behind our room. Somewhere between pond and flood prevention ditch that was very much doing its job. The breakfast in the morning was pretty good though, with dragon fruit, bananas, pineapple and eggs made to order. They had some baguettes that I was surprised to learn were filled with a sweet custard, and then got some amusement out of watching other travelers bite into them & exhibit similar surprise.
Ninh Binh is near the coast close enough to Cat Ba/Ha Long Bay such that there are limsetone mountains similar to the islands in the bays albeit bursting from the land rather than the sea. There are a few common sites to see the mountains, although it is cloudy and misty today so we aren't sure what we'll be able to see. We start by going to the vicinity of Hang Múa to hike up to some Buddhist shrines that overlook a river through the mountains on one side and some rice fields on the other side. This place was confusing and ended up feeling a bit like Disneyland, I think partially because it was a long weekend for a Vietnamese holiday, so there were a lot of local people visiting. But basically, we arrive and pay for entry (100,000 VND) entry into the "park", which has a central path that goes along various restaurants, cafes, spas, and even some small hotels. At the end are the paths up to the shrines: a pagoda and a long statue of a dragon. The dragon is higher than the pagoda, so that's what we decide to hike to. It's 500 steps to the top, which feels longer than expected, probably because the steps are made of cut stones and are somewhat irregular. Eventually we get to the top and although it's not very clear, we still get some good views.
After hiking back down, we get a Grab to the Hoa Lu Anciet Capital. Once through the main gate, there are some wide streets full of people walkig around, and a central park area that seems to be used as a sort of fairgrounds. There was a stage being assembled, as well as some booths set up around the edge of the park. Near this park area, there is a temple that reminds me of the Temple of Literature in Hanoi, consisting of some smaller walls enclosing some gardens, fish ponds, and some buildings containing shrines. In fron of one of these shrines, there is some kind of a ceremony setting up. From what we can tell, it is a celebration day for a previous king. There are some folks playing instruments, and 20 or so women wearing traditional robes. We wait around for a while to see if the women will start dancing, but suddenly a little girl comes up to us with her mom to practice her English! We chat with them for probably 20 minutes. While we are talking the costumed women start dancing, but we decide to keep chatting with the little girl and her mom before leaving the temple. Right outside, there is another gates that lead out into a local village. There is a great feeling of being surrounded by the mountains here.
The person that checked us into our homestay (which ended up being like a hotel/motel) recommended that we go to something called the Thung Nham Bird Park around sunset to see the cranes, egrets, and herons fly back to their roosts for the night. We weren't really sure what to expect, but were still surprised when we arrived. It was a way bigger operation than we expected, an ecovillage/park similar to Hang Mua, the park filling most of a valley between some limestone mountains. Dozens of tour buses go in & out and are parked out front. There is a whole road system inside the park for the electric carts, but we just decided to walk through it. There are a few lakes in the valley that the roads wrap around, with the lake that the birds roost in at the back of the park. The majority of the park in front of that is dedicated to manicured lawns, gardens, and hedges, with some bonsai tress that I can only imagine are hundreds of years old. I wonder how this park managed to inherit them.
When we get to the back of the park, there is a hiking path that goes up to a viewing point to see the birds, however the majority of the visitors opt to take a boat ride out to the birds. From the viewing platform, we can see many boats paddle out, spin around and head back, watching the birds land in the trees like us. A closer view, but much more brief.
I also found this cool bug while wwaching the birds!
It was dark by the time we got back to the front gate of the bird garden, and we were a bit worried about the logistics of getting a Grab where the road dead ends in the bird garden valley, so we walk up the road a bit. Eventually we get someone to accept our ride request, although some bad timing when he's pulling up means a taxi thinks we are flagging him down instead. The taxi and Grab driver both pull over and have some kind of an argument that we can't understand. Eventually the taxi driver leaves towards the bird garden, and the Grab driver motions us to get in his car. Kaila uses her translator app to ask if everything is okay, and the driver says yes. Kaila apoogizes if we put him in an awkward situation and he says "no, no, no" effusively, then translates something along the lines of "the taxi drivers get mad if we pick up people here, but I'm not afraid of them." After he shows us this, he pulls up his shirt sleeve showing his tattoo sleeve. Pretty funny interaction, and we make sure to give him a big tip for picking us up. We go back to our room, since we're exhausted from what was at first going to be a rest day, but ended up being about 11 miles of walking instead.
Sunday, April 6th - Bus to Phong Nha
Today we actually take it easy, waking up with just enough time to get some breakfast at the hotel before it ends at 9 am. We book a bus to Phong Nha for the evening through the hotel, which means we can store our bags at the front desk and get a ride from here to the bus station around 6:30 pm. We go back to the room after to shower, pack, and take it easy for a couple hours. It's pretty rainy, so we are happy to stay inside. When we need to check out, we walk up the street to a coffee shop called Peaceful Zone. We get some coffee and I get an egg and pate bahn mi. We read for a bit, and eventually another couple comes in that we start chatting with: Ben & Kat from Anchorage, Alaska. They've been in Vietnam for a few days, but leave today for the Philipines. They were also on Cat Ba Island, and tell us about a "traditional Vietnamese house." After talking about it for some time, we realize they're talking about the French colonial houses we saw a few days ago during our Ha Long tour! They told us they booked through AirBnB, so we later found the listing and learned that those rooms rent for 200 USD a night, and they were in fact listed as "Vietnamese traditional house," so I guess that's some good reclaiming by the family that owns the property. Eventually we feel like we need a change of scenery, so we take a Grab to a beer garden on the edge of the Tam Coc main street. We get some noodle bowls here that Kaila read she could eat, then we walk around the Tam Coc main street. It's small in the sense that most of the restaurants and businesses are on the main street, but the street is long and full of people. It also seems like there are residences beyond the main corridor. There's a big pond/small lake at the center of town, and folks taking tourists out on boat rides. There are many hotels here, so I would recommend that people stay on the main street to be a little closer to the action instead of what we did.
After walking around, we get a grab back to the hotel one last time to get our bags and get a ride to the bus station. This time we booked a VIP sleeper bus. Instead of the three columns of half recliner, half bunk bed style seats, the VIP sleeper buses have only two columns, with two pods stacked on top of each other. More of a cubby with a reclining seat than a bunk bed.
This is nice because this is the first overnight bus trip we've booked.
This also feels like a good time to point out this surprising fascination folks in Vietnam seem to have with Tom & Jerry. One of our tour guides mentioned it at some point, then I just started seeing Tom & Jerry things everywhere! Mostly on shirts and as decals on the side of semi trucks, scooters, and cars. This is something we didn't see for any other cartoon characters! Here are some decals we saw on a bus:
We don't want to have the full overnight bus experience where we start our next day as soon as we arrive, so we opted for a slightly earlier bus that will get us to Phong Nha around 2:30 am then also booked a hotel to catch a few more hours of sleep before the next day. The cables of the day today are from right behund the hotel
Monday, April 7th - Our first motorbike experience!
Breakfast at this hotel is nice! More eggs ready to order, bread, and lots of fruit: bananas, mango, pineapple, and pink dragonfruit! The coffee is also good. Today we want to go to the National Park, and during breakfast we decide that this might be a good place to try renting a motorbike for the first time since the surrounding roads are the least busy we've seen so far. The hotel rents motorbikes for 100k VND a day (~4 USD), plus gas (which ended up costing another 100k). But first, some lunch at one of the few restaurants in town, a place called Bamboo Chopsticks. The restaurant has a big menu, with western and Vietnamese options. I decide to try some fried chicken with passion fruit sauce and rice.
During lunch, we decide we'll go out to a cave called Paradise Cave, and we set off on the motrbike. The ride out is beautiful! It's also not too scary even though it's the first time I've drive a motorbike. Pretty similar to an e-bike, just heavier. I'm glad to be trying it out on relatively empty roads though, and there aren't many twists and turns we have to watch out for. It's so amazing to see the 360 views of the mountains as we ride. Kaila takes some videos while riding on the back and we were able to get a cool shot of the road by exporting one of the video frames.
Even with both views, it's hard to get the scale down through a 2D photo. Plus, there was much more cave beyond that! A truly amazing size. We walked 0.6 miles total into the cave before turning around and walking back out. To put that into perspective, here's a map that shows the octagonal viewing platform the photo above was taken from, as well as the rest of the cave after that!
After making our way out of the cave, we take the motorbike back into Phong Nha Town and grab some dinner at a restaraunt called Bamboo Chopsticks before retiring to our hotel room. The cables of the day are some lighting cables that were running out of a pond inside the cave!
Tuesday, April 8th - The swimming underground part
Today Kaila and I booked a tour with a company called Oxalis that Nathan from Australia recommended to us while we were on a tour together in Sapa. This company has some different options for tours in the Tú Làn Caves System and other caves nearby, including Sơn Đoòng Cave, the largest cave in the world by volume. That tour gets booked out months in advance (and is very expensive at 3,000 USD per person). For the multiday tour options, the groups camp out in the jungle, but we decided to do a single day tour so we could head back to Phong Nha Town after. We have a quick breakfast at the hotel before being picked up in a van with the folks that will be doing the tour with and we all head out to the Oxalis office together. This group is made up of Paulina and Stewart from Canada, Casey from North Carolina, and Lucy from London who is moving to Australia. When we get to the office, we meet our guide, Hoai, have a safety briefing, and go over the plan for the day. Hoai gives us some gear for the day: army shoes, floating backpacks, helmets, headlamps, and dry containers.
We start our hike out into the jungle from the office. At first it's not actually much of a hike, but a walk down a dirt road out through some farmland where locals grow various crops, including elephant grass to feed water buffalos, corn to eat, and acacia to be used to make paper. Motorbikes occasionally zip past, carrying hauling materials to or from the farms.
Hoai tells us that in the rainy season, this area floods so much that it looks like another Ha Long Bay. He shows us some pictures of how high the water got during some flooding from recent years. He tells us the locals take their livestock to higher ground in the mountains before flooding starts, but they used to stay behind and live in the attics of their houses during the worst of the floods. The recent floods have been so high though that this isn't possible anymore, and some folks had to break through their roofs to be rescued from water rising to record levels. He tells us that a few years ago, some folks visitng the floating villages in the Mekong River delta had the idea to bring the idea of floating houses back to this area, and the company Oxalis has a foundation to help more locals build houses that have big pontoons attached so they can rise with the flood water.
Eventually we come to a river about 100 feet across and only a foot or so deep that we cross to head up to our first cave, Chuột (Rat) Cave. On the otherside of the river we get into the true jungle foliage, but we aren't hiking through it for long before we get to Rat Cave. The entrance of this cave is enormous, big enough to fit multiple houses. Hoai tells us that we'll be doing a loop through the cave and exiting this same way.
We descend into the cave, stopping briefly once we reach the floor of the entrance to put on our helmets and headlamps. The headlamps become necessary quickly as we round the corner from the entrance and the light pouring in through the entrance no longer shines along the direction we're moving.
The cave stays just as tall and wide as it is at the entrance as we continue deeper inside. Beautiful cave formations cling to the ceilings and adourn the walls. The calcium carbonate formations deposited from the dissolved limestone dripping through cracks in the cave take on different colors due to other minerals present: yellows from sulfur, reds and oranges from iron, blue and green from copper, and white from calcium. In some places columns form connecting the stalactites and stalagmites, looking like organ pipes in some places and organic musculature in others. Sometimes the features look like layers of trees or fungus, fractal branches so complex it's hard to believe it's not the side effect of life. We follow a path between these features and eventually get to a point where we start curving back towards the entrance. Kaila asks the group if we can all turn off our lights, and we have a few minutes of pure darkness that our group is respectful enough to match with silence. It's a very human moment, to choose to have these minutes of peace together in a place that is so naturally surreal.
Eventually, we all put our lights back on and continue walking, it feels roughly like we're going back the direction we came, and soon we start to see daylight coming from around a corner up ahead. We come back to the mouth of the cave and have a snack before heading up through some more jungle. We hike through the jungle over what Hoai calls "baby hill" to get to the next cave, Ton Cave, which holds the underground river.
An hour or so of hiking brings us to the cave entracen, where we once again put on our helmets and headlamps. As we enter the cave, we see some cracks in the walls that have eggshells in them, and Hoai tells us these are from lizards. Someone in our group points out something shining up high on the opposite cave wall, and Hoai asks us to guess what it is. At first I think water droplets, but then I remember the trick you can do in any open field with a flashlight at night. Hold it down low, and scan the ground carfully, and you can see hundreds of little pinpoints shining back. Sometimes they look like they're in pairs, but if your eyes were a bit sharper, you might see that each pinpoint is actually eight tiny pinpoints of spider eyes staring back! Hoai says he thinks these are tarantulas, since they're so large. We all watch the eyes together, and eventually see the brown shape of the spider scurry around the rock and realize it must be big for us to have seen that movement from across the cave.
After a few more minutes of walking through the cave, we come to a large cliff where we can really appreciate the size of the cave. There is a 13 meter tall lader here reaching down, and from our vantage point we can barely make out the reflection of out lights on the river at this lower level. Hoai points out a dead tree on the opposite cave wall about the same height up as us that shows how high the water gets when this cave is flooded during rainy season. There are some harness waiting for us at the top of the ladder, which we all put on then take turns clipping onto a safety rope (connected to an autolock device to brake any falls) and descend the ladder.
At the bottom of the ladder, we find one of those big spiders on the ground close enough to us that we can inspect it. I don't think it's a tarantula, but it's big enough that if you put it in your hand (wouldn't be a good idea, but if you did), its legs would span across your whole palm. Once we're all down from the ladder and succsefully walk around the spider, we start walking to the bank of the underground river. There is a single canoe here that one of the porters (the nice guys that are bringing our food out here for us) take across the river with all our backpacks). Not enough space for all of us though, so the rest of us put on life jackets from the boat. There are too many rocks to jump in, so we do this funny wade in, then half-step, half-fall forwards into the water that is about as cold as you'd expect water in a cave be. We normalize quickly though, and swim for 10 or 15 minutes until we pop out at a jungle oasis: the spot we'll be having lunch!
Some of us take off our clothes to dry during lunch, but I'm too afraid of putting on still wet clothes so I let my clothes partially dry while they're still on me. I do take off my soggy army shoes though! The lunch the guides have prepared for us is really nice. They have a whole camp set up out here with some wood burning barbecues. We have some coffee to warm up (this doesn't take long since it's hot and sunny) and sit down for a family-style meal consisting of rice, pork with quail eggs, grilled eggplant, fried tofu, cucumbers, mango, and peanuts.
After our lunch, we head over the mountain that we just took the cave through. Hoai calls it "momma hill", which makes sense because it's way more of a climb than the hill from Rat Cave. It takes us a while to get up and over, navigating the mud and rocks, but it was a nice hike through the jungle. I saw some cool bugs:
Once we're over Momma Hill, we cross the river in a different place since we aren't going back to Rat Cave. Then it's a nice and easy walk back to the offic where we shower, change, have a beer, and get our ride back to Phong Nha. We're dropped off at our hotel then Kaila and I go across the street to Treehouse Cafe where she gets some tasty-looking turmeric chicken and I get a seafood pizza, something that I keep seeing on menus but haven't tried yet. It's pretty good and satisfies my craving for cheese.
Wednesday, April 9th - More floating in a cave
Today we booked a bus to Hue, a city in the Central Highlands of Vietnam, but it's not til 3 pm so we have a good amount of day to spend. We decide we'll check out Phong Nha Cave, a cave that you can hire a boat to take you into from town. We have our breakfast at the hotel, then walk the 10 minutes down the main street to the boat station. We find the ticket counter and there are a few folks ahead of us that seem confused but are talking with the counter attendants. It's confusing, but apparently we can share a boat with others to make the ride cheaper. Makes sense! Eventually we have enough people, and we pay and head to the boats. Some folks split off to go to the bathroom before the boat ride, and while we're chatting with some of our fellow passengers, we meet someone, Aubrey, from Colorado! But not only are they from CO, they live in the same neighborhood we were living in the brief time we moved back before we started this trip. This is the first fellow Coloradan we've met, so it's funny how close we live back home.
We all get on the boat (one guy who was waiting for a sandwich almost doesn't), and we set off for the cave, all 12ish of us impressively paddled forward by only two people! It takes us 20 or 30 minutes to get to the cave and we don't really know what to expect at this point, if we'll be dropped off in front, or at the mouth of the cave, but it becomes clear that the boat is taking us deep into the cave, which is a nice surprise.
It's cool to see the inside of a cave this large from the water! We are paddled deep into the cave (probably at least another 15 minutes) and we see huge features. The stalactites are especially impressive since the flooded cave has no stalagmites to meet their growth and turn them into columns. The roof of the cave is generally about 50 feet above us, but in som places it's higher, seeming more like one or two hundred feet above our heads.
Once we get back towards the entrance of the cave, the boat docks and our talented paddlers tell us we can walk around for a half hour and they will meet us at a spot outside the cave, where this path will enventually lead us. So we get to explore some more cave features.
We get back on the boat, and head back to the boat station. This gets us back into town with about an hour before our bus, so I grab a bahn mi and Kaila gets a smoothie. Then we're on a bus to Hue, this trip only a few hours long.
Thanks for reading!
