The "24 hour rule" is not really a hard and fast rule. The U.S. Air Force says you should wait 24 hours before you board a plane after scuba diving. OTOH, the U.S. Navy's recommended minimum pre-flight interval is
only TWO hours. PADI's Flying After Diving guidelines fall somewhere in between, saying that you should not go to an altitude (fly) within 12 hours of completing a single dive or 18 hours when doing multiple dives (but where
possible wait 24 hours). And DAN, the leading organization for diver safety issues, also recommends something in between with 12 hours for their minimum surface interval before flying. So which guideline should you use. Personally, I think DAN is probably the most authoritative when it comes to diver safety and medical issues and their guidelines state:
Quote:
Revised Flying After Diving Guidelines for Recreational Diving - May 2002
The following guidelines are the consensus of attendees at the 2002 Flying After Diving Workshop. They apply to air dives followed by flights at cabin altitudes of 2,000 to 8,000 feet (610 to 2,438 meters) for divers who do not have symptoms of decompression sickness (DCS). The recommended preflight surface intervals do not guarantee avoidance of DCS. Longer surface intervals will reduce DCS risk further.
* For a single no-decompression dive, a minimum preflight surface interval of 12 hours is suggested.
* For multiple dives per day or multiple days of diving, a minimum preflight surface interval of 18 hours is suggested.
* For dives requiring decompression stops, there is little evidence on which to base a recommendation and a preflight surface interval substantially longer than 18 hours appears prudent.
(source
http://www.diversalertnetwork.org/medical/faq/Flying_After_Diving)
Since you're staying over Saturday night, you probably could get away with flying back the next morning (even though it would be something a little less than the minimum 18 recommended by DAN, but if I were you I'd probably drive back simply to enjoy the truly awesome scenery along the way from a ground level (entirely different than the bird's eye view) if not also to be extra cautious about DCS. As others have stated, renting a car just for that drive wouldn't really be cost effective, particularly because of the extra pick-up/drop-off charges that would be involved in returning the car to a different location than where you got it. And, since you were even considering renting a car, "roughing it" by returning by public bus for $6 would probably be out as well (even though it doesn't really rough it all that much). So, using a tourist shuttle would probably be your next best way to go. Interbus has an 8:30AM departure for $45 ($42.75 if booked through
http://www.shuttlebus.co.cr) or you return with Grayline leaving at 7:15AM for $44 (
http://www.graylinecostarica.com/graylinetouristbus.phpBTW, and not to burst your bubble, but I agree with Scuba1 re: diving in CR. There is probably a good reason why you can't find much info on diving in the MA area and why there aren't more companies offering it. Of course, the fact that you couldn't find much on SCUBA diving on THIS site should not be too surprising since most of the guys around here are mostly just interested in MUFF diving, but it still doesn't get much better elsewhere. If you Google "scuba" and "costa rica", what you WILL find is much more info on diving elsewhere in CR other than MA. It is true that Canos Island (much further south along the Pacific coast) reportedly has some really great diving, but to go there you have to go out of Drake Bay which is much harder to get to/from than MA, particularly if you plan on returning to SJ from there without flying. Cocos Island, way off the Pacific coast would be even better for diving but trips there typically involve multi-day packages aboard dive-boats. And if you're looking for coral reefs than only place in CR where you'll find that will actually be near Cahuita on the CARIBBEAN side. Otherwise, you'll have to settle for cliff dives and pelagic sea life as the main attractions (though that can be pretty cool as well). The main problem with diving in CR in general is visibility. Unlike other Central American countries (notably Belize and Honduras, which also have awesome coral reefs offshore) CR has both a verdant onshore bio-system coupled with steep mountains that run down close to the shore (particularly along the central Pacific coast) resulting in lots of organic run-off which clouds the waters. This can especially be a problem during the rainy season, which will be at its height when you go down in September. Gatorsrule's terse review neglected to mention what time of year he went but I suspect it was probably during the dry season when conditions are normally at their prime. My recommendation would be to do your diving elsewhere in Costa Rica OR save it for some future trip that falls during the dry season.