what happen in chapter 30 and 31

Chapter 30- The men discover a vast sheet of water that the Professor promptly names the Liedenbrock Sea. The water glowed with light above it was a sky of vapour. After Axel regained his strength, the men moved on and followed the winding of the shore until they came upon a high, tufted forest filled with vegetation they'd never before seen. Upon closer inspection, they realized they had entered a forest of giant mushrooms. Before going to sleep, they talked about the creatures that may have once, and still might, exist there.

Chapter 31- Axel awakens and takes a bath in the sea. The group was thirty-five leagues below the surface. Uncle tells Axel they will take a raft to the next level. They build the raft and depart upon the Liedenbrock Sea