I really like the first one with the boat and the people. You applied the rule of thirds well there.

I find shots of an empty sea always a bit boring. When I shoot seas I hope for boats, people, some interesting clouds or at least the sun. But as Mick Jagger says; You can't always get what you want 😃

Do pay attention to have a straight horizon. Some of them are a bit skewed.
And as I said in a reaction on a blog by @katerinaramm; I wonder where the water goes then 😃

Bit in your first, and in my opinion best shot, itnis perfectly straight!