I feel so sorry for them. They are so desperatly trying to rid themselves of their boredom. Beaching themselves is not playing, this is unnatural behaviour.
According to whom? If you put slideouts in coves and bays, etc. I guarantee that you would see wild orcas playing on them. Three generations of this orca family do this all the time because they love it. Their mother teaches them to do it. It is playing. What are they supposed to do all day? Read? Go to the mall? Watch television? You activists need a new hobby.
