Downriggin,

That is interesting. I know there was a sea otter hanging around Tacoma a while back that was moved back out to the coast.

The next time you see one, watch it for a while and notice the behavior. Like I said, sea otters will swim almost exclusively on their back and will rarely come out on land. River otters swim belly down and come out on land often ... and are commonly found in the salt water. If you feel comfortable that it might be a sea otter, I would give WDFW a call.

Cheers
josh