Here's the translation of your text into English:
It is now the 4th day since I arrived here. I ask anyone who finds this letter to call for help. I am somewhere on an island in the open ocean. I accidentally ended up here as a result of my ship's crash. I am John Myers, and I was the backup captain of that ship. I remember nothing from that day because I was sleeping after a long shift. I can assume that the crash happened at night. I woke up in the open ocean closer to morning and immediately saw a few islands. I decided to swim to the nearest one. Then I thought I needed to find something here, but the island is uninhabited and there is almost nothing here except a palm tree, some coconuts, and some thorny bushes. I immediately decided to swim to other islands. As it turned out, the water between them is very shallow, but these terrible sea urchins, as I know, can be eaten, but I can't reach them in any way. As I remember, our ship was heading towards India from Thailand. I ask for help; I can survive for another two days, but I won't last longer.
If you need the translation to be formal, informal, or adapted for a specific purpose, let me know!