Your swimming partners

I often swam in our backyard "pool", the canal. the water is clear that I can see my feet so I really felt very comfortable. I saw a few fish and gently rolled onto my back for some backstroke. I felt a rush of water under me and warmth! I did not think there were warm springs in the canal. I then felt a rush of water again and thought crocodile! I yelped first and then realized I felt warmth with the push of the water. A neighbor laughed and said that there have been two manatees swimming with you! Well, they escorted me the rest of the way down the canal, back to my dock.