The odyssey is fantastic. We went 2 years ago. My son did the San Francisco - 176' - on a single tank. I think he had 10 minutes or so on the wreck. He's young, strong, very healthy and doesn't use a lot of air. Everyone else had doubles. Most of us, though, did an alternate dive -- they give you so many choices to dive, that by the time the San Francisco dive comes along, you won't feel badly if you opt out. I went on the trip thinking I'd try the San Francisco, and didn't hesitate a minute to go on the other dive instead.
You MUST have a backup computer. You must. Rent one from your local dive shop for the week. I don't recall the Odyssey having any extra computers on board. But you can't just switch from a computer to tables or another computer - they'll make you wait 24 hours (those were our captain's rules, and he was firm about this). So you have to be diving 2 computers the whole time in order to have a backup. If you're forced to wait 24 hours, that's quite an expense to endure for not bringing a second computer. We each owned our own computer and then each rented one for the 10 days we were gone. Since we booked through our local dive shop, they were very willing to rent us computers to take as backups. My son's did crap out, so he did end up having to go to his backup. And you do not want to dive tables - much to conservative for this experience.
I know the Blue Lagoon is cheaper, but we really really loved being on the Odyssey.
We spent 3 days in Hawaii on the way out (I highly recommend this, and you can make this happen fairly cheaply) and then the way back was straight through.
btw, I'm a single mom and funds are always tight. We saved (for my son - think paper routes and cutting lawns; for me - counting every penny and lots of mac & cheese) for 4 years, and I still had to use a credit card that I just finished paying off. Totally worth it. I feel that if we could find a way to get there, anybody can.
---------- Post added May 3rd, 2013 at 10:27 PM ----------
Odyssey temps - we started the week using dive skins and ended the week diving in swim suits. You won't need 3 mm or 5 mm.