(may i alter the world just a little, please?

nothing too fancy.)
atomtengeralattjaro was sailing in an unknown sea, deep below the surface. He stumbled upon what looked like an island, so he navigated closer. The coast was high and rocky at the southern part of the island, and he found a natural underwater tunnel in the rocks. It was spacious enough for him to fit in, but he couldn't turn inside. Curiousity led him in anyways, because there was a dim light coming from the end of the tunnel. He sailed through carefully, as not to scratch his body on the sharp rocks.
atomtengeralattjaro reached the source of the light: it seemed like a small artificial lake of sorts, and when he surfaced and looked around, he gasped in awe: he was inside a huge room shaped like an A. The room was so large the small lake didn't even take up a fifth of it. The rest was full of strange and awesome Christmas decoration, and was very well lit, atomtengeralattjaro needed time to get accustomed to the brightness.
He waited to see if anyone else shows up in this strange place.