Yep, unfortunately Scott got it right. They are Industrial kitchen exhaust fans. If you blow them up, you can see the huge blower motor, and the white conduit line for the electrical lines. From the looks of the other one on the left, it appears that they are housing the actual exhaust in a metal mesh housing to disguise them as part of a larger structure. It is strange they would install these by the pool. But as the say, the path of least resistance is a straight line. Just my 2 cents, but the are in-fact commercial exhaust fans.