"I like living by ocean" is incorrect. You need to say "the ocean."
There are several considerations for how you should form the sentence you're describing.
1: Do you currently live near the ocean, and you're telling someone that you are happy that you live near the ocean? - OR - Are you looking for a new place to live and you are telling someone that you'd prefer to live somewhere closer to the ocean?
If you are expressing that you are happy with your current situation I would use the verb "like". ie: "I like living near the ocean."
If you are expressing your general preference I would use the verb "prefer". ie: "I prefer to live near the ocean."
2: Whether you should say the "Ocean" or the "Sea" or something else depends on what body of water you are referring to.
If you're expressing a general preference I would say "Ocean" or "Coast".
If you're expressing a desire to live near a specific body of water I would use whatever noun the local people use for it. For instance, near the Gulf of Mexico you would say: "I prefer to live near the Gulf."
Typically whatever "water word" is used as part of the name of the body of water is going to be how people refer to the body of water in the absense of it's formal name. ie:
- Lake John Doe == "The Lake"
- The North Sea == "The Sea"
- The Gulf of Mexico == "The Gulf"
- The Pacific Ocean == "The Ocean"
3: How close do you want to be to the water?
If you just want to be within a few hours, just say: "I prefer to live near the ocean."
If you want to specifically be within a few minutes from the water, you should not say Ocean or Lake etc. You should say "the beach." ie. "I like living by the beach."
"By the beach" or "on the beach" imply much closer proximity.
4: The best "general purpose" word is neither Sea nor Ocean, it is "Coast."
ie. "I like living near the coast," or "I prefer to live by the coast."
5: There's a big difference between "by" the ocean and "on" the coast.
Note the critical distinction, if you say "on" the coast or "on" the beach you mean you want to be right at the waters edge, whereas if you say "by" the beach or "by" the ocean you just mean within an accessible distance.
Hope this helps.