I once anchored in 35 ft in CGB and payed out the chain only to find out it wasn't attached at the bitter end. There was only about 150 ft of unmarked chain, and you couldn't really see into the locker to gauge it's progress. Fun afternoon holding station with no anchor and free diving 35ft in cloudy water to find the chain.

We eventually grabbed a late-appearing mooring and got the chain next morning when the swell died so you could see more than 5 ft on the bottom.

Since then I always check to see that the chain's bitter end is secured, and the lengths are marked somehow so you know how much you are paying out.