Anchoring is primarily limited by the scope, or ration, of the length of the rode (anchor line) to the dept of the water. 3:12 if it's a calm day and you're stopped for lunch or to watch bikini herds in their native environment. Sleeping in a protected cove, 5:1. A little wind blowing 7:1. And add for the height of the bow. SO . . . calm night, drop anchor in 25 feet, let out 150' of rode. It there was 60 feet below me, I'd need 325 feet out.
And what is this about DIVING on the anchor??? I don't THINK so!