We saw the same amount as your pic the last time we were in Poulsbo, really cool, and it looked like you could walk on the water there were so many. We had dropped kayaks and were paddling to town from anchor when we first saw them, and later they surrounded our boat. They don't sting and my 2 and 4 year olds (esp the 2 year old boy) thought it was the coolest thing ever to pet them!!!
(I thought it was really cool too, but I didn't know they didn't sting until I got up the guts to do some "sample petting" before my kids tried! )
Be careful, the smooth tops aren't stingy but the tentacles underneath are!