It would be the equivalent of wearing eight layers of clothing and then trying to jog a marathon.
Their transparent fur would also make them poor hunters and speaking of which, what would they eat on a tropical island once free? There are no seals, nor would there be large enough fish in shallow waters to sustain them. Boar are a possibility, but the nutritional changes would probably make the bears sick more than it would nourish them.
Also, if the only route to the island was via submarine, are we to believe that Dharma stuffed multiple polar bears into a submarine? It literally is impossible.
There are more practical animals that Dharma would have chosen. If they wanted an animal that was similar to a human, there are monkeys, rats and even pigs (which were already on the island to begin with).
They also gave a strong impression that the bears had been free for some time, so I would have expected them to die off long before the 815 survivors arrived.
Jacob drew people to the island, but at the same time, it was stated that Jacob's way was to not allow people to leave, or if they did leave, make it nigh impossible to return. Setting up a submarine trade route would be incredibly difficult. Again, there's no purpose to it either.
So while the answers are kinda there, they make no sense and it is akin to stating that the moon is made of cheese that was thrown into the sky by a giant cow who eats part of the cheese wheel every day as a means of explaining the existence and phases of the moon. It's utter rubbish and nonsense.
And please forgive me for going off topic (and for the use of a conjunction at the start of a sentence). I initially did not realize that there was a lost topic in general and would like to continue discussion there, thank you.