I can help
what spanish are you in?
I think it's nadar because "va al mar" means he is going to the sea. Therefore, he would be going to swim.
Answer:
1: en (not pretty sure abt this one
3: unida (not sure too)
5: jugar
I'm a native spanish speaker and I think this is quite hard lol
If it is the future tense it is tendra.