I would guess about 1.5 hrs. We were doing a recreational dive. We dropped he and 4 buddies off, gave them a bearing to our mooring pin, and then it took us maybe 30 minutes to get to our pin and to get in. On our way out on the wall they passed us at about 60ish feet on their way to the boat. His buddies only did 300' and I'm not sure if he was at the same level when we passed. He said he did the first 160' back up in 1 minute. He did breathe O2 as a planned precautionary once on the boat. He beat us back on the boat so not sure of exact times.
Doubt you can do 550' in 1.5 hours. My software says that dive is more than 180 minutes from surface to surface, even if you're there only a second. How many bottles were in the water with him?
---------- Post added March 26th, 2015 at 09:57 PM ----------
Spoke to one of his dive buddies this am who is also a DM for the shop. He said he actually did over the 550 and went 565' in 62 minutes. The next step up to 800' will be a 7 hr dive. That's their claim.
Nope, quit believing everything you hear.
For the rest of you who believe this, quit believing everything you read.