First of all, a few tips. Before you go there, check out the map. There are two parking lots, one is a bit closer but paid and another one is a 5 min walk - but free. So pick what you prefer. Next, the hot spring is close to the edge of water, so you should try to arrive within a couple hours (before or after) from the low tide. Then you find the spring - the water is about 60C, so it's very hot. Most people would try to dig a little pool and if you do it right above the spring - it would be to hot to tolerate. So you should probably dig it a little bit on the side so you can mix the hot and cold water to regulate the temperature.
Overall, it's a fun place to visit. Highly recommended.