Where we fish at Cape Cod, there's a large colony of grey seals.
The seals are curious and smart. The little ones like to play "tag" and will swim up within a rods length, make a big splash and swim off.
Adults will follow you down the beach and wait for you to hook a fish, then "liberate" it from you. .... your drag can really get a work out from that.
Like I said, these beasts are smart, and will stay out of sight, over your shoulder, until they're ready to make their move.
My buddy and I were fishing the big surf one day last month.
I had my back to him but when he started yelling I turned around to quite a sight
He was backing up the steep beach about as fast as he could go, dragging a big striper in the sand with a full sized (600-700 lb) bull seal in hot pursuit
Of course once the seal was fully out of the water, it slowed down considerably.
When my buddy realized that the seal wasn't about to attack....HE RUSHED THE SEAL .... shaking his rod and screaming
The seal backed up, swam off, my buddy was shaking like a leaf, and I'm laughing my fool head off