Thanks for the info guys. Actually, we’re planning a trip to Cozumel and there are some shark dives offered there. From my research it looks like the DMs are pretty good about judging your abilities before they "throw you to the sharks." I haven’t heard of anybody that has actually had to pull out their log book and prove how many dives they have been on. Plus, the log book is only as accurate and honest as the person who filled it out