Let me set the stage:
Kansas-raised, 225 pounds(50 pounds ago) & 6'1", the only diving experience was in a pool at the Y. On a paddleboat in the Bahamas with my wife(who was trying to read a book of all things), sliding off the boat into what I thought was 4-5 foot of water to begin my snorkeling experience. As I drifted down into what was really about 10' of water, I watched as my fin touched the beautiful white sands of the cove.
Then all hell broke loose! A 6' or maybe a 16' stingray came out of the sand where my fin had touched. As my wife tells the story..... I came out of the water like a missle and landed standing on the boat without the use of my hands. Needless to say, my wife still laughs about her Big, Brave Husband to everyone we meet. My story is that I was testing the "true propulsion" capabilities of rubber rental fins.
BarO