You grab a tree to help you reach the bar out in the ocean, using it as a jetty leading straight to it. Now you can walk out on your makeshift pier and go get drinks without needing a boat or getting wet.

You also made this jetty so it would be easier for Santa-san (さん) to dock his sleigh. Oh, you didn't know? His sleigh is more of a speed boat now, and he wants a refreshing drink after delivering all those presents. You get extra presents for making him a jetty, so win-win.