Grotto Spring is also a small geyser with an erratic eruption interval ranging from one hour to two days. Between eruptions there is a constant gurgling sound of steam boiling from the spring (Schreier, 2005).

The unusual siliceous sinter deposits around the geyser are about 8 feet high. They are forming from the splashing of water during eruptions that, in turn, evaporates, leaving behind the mineral deposits. Click here to see a recent photograph of Grotto Spring.