I'm writing this from inside the crater. I'm on a ledge about halfway down. I'm exhausted.
I woke up this morning resolved to see how far into the crater I could get. In some ways, that could be seen as a death wish, but I don't have supplies for much longer anyway, and I felt compelled to find out what would happen when I put the phenomenon to the test.
When the sea was there, I kept my eyes open and waded in as deeply as I could. When the water was at my chin, and I could only just feel the ground with my toes, I shut my eyes. I felt my weight drop down as the water disappeared. I stood with my eyes closed, giving them as much time to recover as I could. I opened them, and walked quickly down the rest of the slope. I reached the edge and looked over. It was steep, but nowhere near vertical. I'd been lucky, and found a part I could scramble down without ropes or equipment. I started to descend. My eyes were burning, and I had to concentrate on holding them open. My vision blurred, and when it became too much, I braced myself on the surface, took a deep breath, and slammed my eyes shut.
I waited there, crouched on the crater wall with my eyes closed. I was still dry. I opened them. The crater stayed as it was while I blinked. It had been fixed as a sea when I arrived; now, it seemed to be fixed as a crater. I scrambled back up and went to my bag. The crater didn't change. I took the bag and climbed down.