A quick geology lesson. The Salton Sea is below sea level because it's a place in the Earth's crust that is thinning and dropping as a new spreading center is trying to develop. The result would be the Gulf of California spreading northward possibly up to Death Valley. This all means that there is a heat source fairly close to the surface. There are numerous geothermal plants in the area. It's a very seismically active area as well. There have been a few M7+ earthquakes in the area over the past few decades including one just a couple of years ago. The bottom line is that this is a very geologically active area. Here is a pic of some of the mud pots and hot springs we visited (note geothermal plant in the background).
Since this is not a national park and is not well-publicized, there are only a couple warning signs but not much else. You're on your own as to what risks you take. Fortunately deep, sticky mud is a good deterrent to getting too close. You start heading for a mud volcano, but then you start to sink in and you quickly back up. I finally found a spring that I could approach. Let's just say that the water was VERY toasty.
We then went to an area that I was very familiar with. There were mud volcanoes, but they were largely driven by CO2 gas and not hot water. For years afterwards I had yiffy WAM dreams about re-visiting the area. tilt_longtail would have been so envious! I was saddened, however, to see that the area was largely dead now. A geothermal plant had been constructed a stone's throw away and it appeared that the plant had caused a reduction in ground water or pressure. There were still a few active features, but it was not nearly as active as before. I did find, however, something to please my wet-and-messy self. It was small but an easily accessible mud volcano with some of the most murrilicous mud. I was quite surprised to find that the mud was very warm to the touch. I'm not sure about totally jumping in nekkid, but a paw was ok.