BTW, a couple direct answers to your direct questions:
- How do you find clear conditions, good spots where charters go
-- kinda mentioned this earlier, but just call one of the local charter companies and ask for recommendations, Keys peeps are pretty easy-going (but do NOT ask them for their lobster spots !!!)
-- water clarity is awesome down here, so not really "good spots, bad spots" in that regard, but also highly dependent on winds/disturbances, so will largely be dictated by the weather
- Safety gear:
-- check the FWC site for mandatory safety gear in FL, mostly standard stuff but we were surprised that FL requires flares or "signaling device" on-board ($50 fine)
-- when you snorkel from the boat you will need a dive flag, we prefer a big flag on the boat, but you can also use the floating flags that you drag along behind you
-- two "optional" considerations, your call: hand-held VHS radio (but you will usually have cell signal inside the reef), SeaTow membership (cheaper than a tow, if needed)
- Bouy hook-ups
-- marked dive sites will have big white mooring balls with a rope that has a loop on the end
-- idle slowly up to the rope and have someone grab the rope with a boat hook
-- take one of your docking ropes, attach it to one of the front cleats, run it thru the loop on the mooring ball rope, then attach the docking rope to the other front cleat, creating a simple sling that ensures your boat drifts parallel with the current
-- if a mooring ball is not available, it is usually ok to drop an anchor but you MUST MUST MUST ensure the anchor is in sand and not on coral or seagrass !!! We usually drop the anchor on a sand patch then dive down to double-check things
Couple other thoughts:
- if you don't own snorkel gear, and if you don't have rentals already lined-up (rentals are not common in the Keys), I recommend stopping at Scuba Outlet at mile market 106 bayside, when you first cross the bridge into Key Largo
- if you plan on tow sports (wakeboard, surf, tubing, etc) then worth checking with a local dive shop or FWC on any restricted areas, or better yet just checkout the OtherSide cable park right there in Marathon