BTPA's Biggest Deficit...

In my humble opinion, the thing that derailed this concept from the beginning--other than not following Gallico's original novel and using faves from the original--was the fact that there was no "event" to bring the characters to common ground.
In the original, there were two catastrophes: the capsize and then the flooding of the ballroom. It seems that without that sort of action, Beyond was just a sad immitation that appeared as though the funds had run out before the film did.

yes, I know the Poseidon explodes toward the end but you see it for a microsecond and the explosion is so HUGE that it should've caused another tidal wave, i.e. Beyond Beyond the Poseidon Adventure?

"Now do you believe a dead rat can float, Lisa?"