Cooper's behavior has gotten much better since I started exercising him. Every day I play fetch in the pool with him for able half an hour. For an extra workout, I throw in his football that has holes in it, so it isn't very boyant. He constantly runs over it, then swims around the pool 2 or 3 times looking for it while it takes its time to get back to the surface. He has to work to get it. This makes for an amusing attempt to get the ball.
The second attempt to get the sunken ball, he decided to dive bomb it.
It's right behind you!
"...It was here a second ago!"
Jake helping Cooper out of the pool

Normally Jake it too fat/slow to run away wen Cooper attacks him, so Jake attacks Cooper when he is weakest: getting out of the pool.
Jake, the coward, running before Cooper figures out what just happened.
That is as far as jake goes in the pool. He can't swim.