There are a couple of hot, or at least warm, springs at Aguacaliente (naturally!) Wildlife Sanctuary in Toledo, near Laguna village. The sanctuary was for awhile and may still be officially closed to visitors, but I think you can get permission to visit. I've been to the sanctuary but not to the hot springs and don't know much about them. These aren't developed or anything, and the main interest for visitors to the sanctuary is wildlife, not the springs.
There also are hot springs near Lake Izabal on Guatemala's Caribbean coast, and at least one in the Yucatán.
Probably there are others.