Riley was feeling so invigorated that he didn't notice right away that he was melting. As the liquid washed over him, Riley's naked flesh became liquid and washed off his body. He was like an ice sculpture under a spout of hot water. He held up his dwindling hand, as he became one with the fountain. At first he was horrified, and then he realized he could still sense his melted flesh. He could feel the water. He was one with the water. The water was one with him. He started to hear voices in the gurgling babble of the waterfall. There were hundreds of other voices, and he was joining the liquid life. Merging minds and bodies in an impossibly miscible state.
If anyone had been there to see it, they would have seen Riley's shrunken form become translucent and splash into pool. He was now liquified.
Just then Sam stumbled upon the waterfall and pool.