Ways they could have got back on (possible spoiler)
There are lots of bad reviews for this movie on this board, but it did hold my attention and had some good performances.
Once they realized that the ladders weren't down and they couldn't get back up then my mind kept coming up with ideas for how they could get back up.
Reaching for the flag was a good idea but maybe the smallest person should have tried it (Michelle?) with two guys thrusting her out of the water. It did look flimsy and they should have predicted it would have ripped with one of the heavier guys trying it.
Couldn't one of the girls have gotten on Dan or one of the other guys' shoulders? It might have taken a few attempts but they could have done it with one guy taking a few deep breaths to get extra-buoyant and the other two guys spotting/helping the girl to get onto the shoulders.
Also, the dolphin idea might have worked with two people spotting from the side and one from the back.
The idea for them to make a rope out of all their swimsuits should have occurred to them a lot sooner and then they should have tried more than just once.
The way they actually did get out would have been the last thing to occur to me and that made the movie more realistic. Of course panic and hysteria would have clouded their minds and it did, which added to the watchability of the movie. The ending was also fairly clever. It also helped not to have sharks this time even though at a couple of points people imagined them.