Do islands sink?

Written 11th May

We all know that islands don’t float above water but they go all the way down to lithosphere (well you get my point). Did the sea level rise to cover the island (at the Flash Sideway time perhaps after the jughead explosion) or perhaps decrease to reveal the island (at the time before the Flash Sideway)? There is not any possible way the whole surface of the island (as we see it on the Season6 premiere) to be undamaged and everything beneath it to be destroyed in order to sink it. Except of course if the island is not really an island (by the definition of it)? If you say that we are dealing with different parallel universes where in each the island happens to be underwater / not underwater, then I rest my case.