When I was a boy between the ages of 6 and 15, my parents used to take us to the Caribe Hilton in Puerto Rico for 10 days around the holidays. I spent all day, every day with my mask fins and snorkel scouring the lagoon for sights of the fish and jewelry that would fall off the other guests while frolicking. It was the 70's and there was a lot.
As the years went on I was able to hold my breath longer and would recognize fish, anemone, and other creatures growing and changing from year to year.
I completely get what he is talking about regarding free diving and his newfound connection to all living things.
I was very lucky to have had the experience I did in P.R. and it would have been wonderful had my life had taken his track.