I have been touched by curious harbor seals on three different occasions. Poked one of them in the nose with my unloaded spear gun, we where abalone diving north of the Russian River, he had nosed/bit my fins multiple times!
I had a pair of river otters get to with in three feet of me a few years ago. When I was diving for red rock crabs.
I have a friend who scuba dives, I only free dive, well he was on the bottom with a full stringer of rockfish. A sea lion decided it was a catered lunch and started in on his stringer. He said that he poked it pretty hard with his spear tip, it finally left him alone.
These are all decent sized carnivores, sometimes they are just playing, and sometimes people loose fingers & eyes!