Alone on a deserted island

After I watched the movie Cast Away on TV, I went to bed and I had the strangest and scariest dream ever!
I dreamed that I was kidnapped by some UFO’s and dropped in the middle of the ocean. The creatures must have been merciful, because I landed somewhere near dry land. I had no idea on which part of the globe it was, or how did the lands’ surroundings look, all I know is that it was some kind of an island. I looked up to the sky but the UFO had already left so I went looking for people. Although I walked around for several hours, I didn’t find anybody else alive on the island. I did find a so called building which looked like a shelter, but there was no sign of people around. I was convinced I’m a part of some kind of extra-terrestrial experiment, but I tried not to think about it. I saw that it’s around six o’clock, and I was hungry, so I looked for something to eat. I found a kind of berry which looked eatable to me, and I tried it. It was sweet, and tasty, so I put some in my pockets too, and I returned to the shelter. I was waiting for someone to show up, but nobody did. I was all alone, and as the night settled in, I was starting to feel more and more frightened. I kept on hearing the sound of the ocean, the wind blowing through the trees and I couldn’t get any sleep all night.
As the daylight slowly enlightened my shelter, I felt a little less frightened, and I went to explore the part of the island where I hadn’t been before. I found out that I’m at the top of some kind of mountain, and that almost half of the island had been sunk.
Suddenly, a terrifying thought popped into my head: “The ocean is going to cover the whole island, and that’s why the shelters’ previous owner had left!”
After I realized the danger I’m in, I wanted to come up with some kind of escape-plan. I looked at the trees, hoping I could build some kind of a boat, but I couldn’t find anything I could chop wood with. Waiting for help looked like a bad idea t