Rondo takes the lead and enters the cave. He cautions the others to hang back with their torches so as to not ruin his infravision, and if the angle turns too steep he will have a rope tried to his waist as a lifeline. What does he see?
He ties a rope around his waist and enters the cave on his hands and knees. About 5' in, the cave opens back up and you can stand comfortably. Infravision tells you that there aren't any warm objects around, but does tell you that the cave entrance is at least 60' long and roughly 10-15' wide, at one point opening to 30' wide before narrowing back down again. You can tell it goes farther than 60' but your infravision doesn't go any farther. It's pretty level without any drops, but filled with boulders, rocks, stalactites, and stalagmites. Moving through here will be pretty slow.
The rest of the party wiggles into the cave, one by one. You all congregate where the "P" is on the map; you can go north-eastish, south, or west (you came from the east).
Will examine the water to make sure it's really water. Won't touch it just yet, but will move close to it, sniff it, examine the depth, color, an consistency, and drop a pebble or something into it if nothing appears out of the ordinary.