1 - You don't go to the sea unless you mean to go to the shore by car (for example). Also, we don't usually use the article here.
LDOCE gives a little difference in meaning. Out to sea means away from the land. Go to sea means to go to work on a ship. Also put to sea means to make a boat go out to sea.
So it would be best to say Let's get on the boat and go out to sea. or Let's get on the boat and put to sea.
As for 3 & 4, 3 could mean that you like to be in the water but very close to shore. 4 could mean that you like to be in the sea far from land. For both of these, I understand it to mean to be in the water, not on a boat.
When you block a person, they can no longer invite you to a private message or post to your profile wall. Replies and comments they make will be collapsed/hidden by default. Finally, you'll never receive email notifications about content they create or likes they designate for your content.
Note: if you proceed, you will no longer be following .