No - and you wouldn't want to either, the pH is about 1. Meaning it's pretty much the most acidic a substance can be. It would be like bathing in stomach acid. And, if that's not enough, the sulphur in the lake produces a strong eggy smell that isn't particularly pleasant. Depending on the conditions and wind direction, you can also smell it at the crater and/or on the ascent. If you want to relax after the Santa Ana Volcano hike, head to the Salto de Malacatiupan hot springs. Here, you can bathe in naturally heated 36 Celsius/97 Fahrenheit volcanic spring water. Perfect for tired muscles after a long hike!