This is a large jjimjilbang and sauna right on the harbor (Western, Seoho-man, just off Jungang-ro Street) in Tongyeong. If you are near the market and the replica of the turtle boat, it is right there. I'm sorry I haven't got more specific directions, but there's a wikimapia
to help! I went on a Saturday around 1 pm, but it was not crowded at all and pretty quiet. The only busy part of the place was exercise classes going on on the floor with the weight room.
The baths are pretty typical, hot, warm, event (maybe green tea? I'm sure it changes), and some laying-down small baths that weren't filled when I went. One nice feature is the cold seawater bath, it runs the length of the room, right against huge windows overlooking the harbor, so the view is great. There are also some steam rooms and saunas. Its an older building, and also this being way off the tourist track, there are many people washing their underwear or spitting in the drains, something you don't seem to see in the city saunas. That said, this sauna does have a more "authentic" feel than the big touristy places like Dragon Hill- it is very relaxed and small-town feeling.
The jjimjilbang is nice, with a large wooden floored area to relax, and a salt room, some warm rooms, no sleeping areas dedicated to that but its dark and quiet so its easy to sleep anywhere. I fell asleep for 3-4 hours and I have a tough time sleeping anywhere usually, let alone in public. There is a restaurant with your average Korean fare, and a weight room and workout floor that looked very well-supplied. Another neat feature is the roof-top foot massage walk, its a trail of spiky rocks and things to massage your feet. It has a great view of the harbor, though I am not too sure about the health benefits to feet, it hurts!
I saw many jjimjilbangs in Tongyeong and there may be better ones out there, but Haesu Land is a nice place to spend some hours if you are waiting for the ferry to one of the outlying islands. it is maybe a 10 minute walk from Haesu Land to the ferry terminal.
*Fun fact! When I googled Tongyeong Haesu Land (in a vain search for photos), it comes up as a wi-fi hotspot on the GlobalRoaming website! :)
117-5, Hangnam-dong, Tongyeong-si, Gyeongsangnam-do
Open 24 Hours
Jjimjilbang 10,000 won
Sauna only ~7,000 won
Wikimapia of Tongyeong Haesu Land