its pretty easy to decipher

Ocean is subconscious (conciousness that connects us all) and gate is your mind. mind guards subconcious just as a gate.
your friends are not your friends but your masks of personality you use in everyday life. Like a roles u play: ur role as a father, ur role as ur job, u role as a son, ur role as a whatever u like do do or appear.

What is the meaning of this dream is that you get connection with ur higher self and your fake parts of your persona dont like it at all. that means u will abandon them soon. in short words - u will wake up, buddy.

why ocean is motionless is very interesting. why dont you ask it from your higher self?