This is one of the least exciting episodes you'll see of "The Undersea World of Jacques Cousteau". This doesn't mean it's bad-- just not as exciting as most. It's also among the earliest episodes in this fabulous series.
There are two main topics in this show--the most important of which is the Cousteau team trying out a new mini sub. They already had one but contracted for a pair of newer ones--subs able to dive deeper and go faster. You see the folks putting it through its paces...and this is pretty dull stuff. Additionally, the team comes upon a lot of beautiful Green Sea Turtles and you not only see them under water but also laying and hatching eggs. And, in the spirit of these old shows, the crew become involved---rescuing some of the baby turtles that would been surely eaten since these guys had the misfortune to be hatched during broad daylight so that the Frigate Birds could easily see them and eat them.