Yes dogs can swim in the Ocean as long as they want to swim and can swim.
I've taken my dogs to Oceans, lakes etc where the dogs were allowed and allowed them to swim in the ocean, lakes etc with me and my family.
The dogs had lots of fun and I just made sure to bathe the dog after we got home to wash any salt water off their fur and skin.
The dogs had a wonderful time in the ocean swimming and I even take them out on the boat with us when we go fishing.
The dogs make the boating and swimming even more fun and I plan to take our dogs out to the ocean and lakes this summer again.