Plenty of cruise ships go across the oceans. Covid has put a damper on the crossings, I don’t know if they are still being done. The ships go faster than a pontoon. I don’t understand why a pontoon, I am missing something. The Cunard ship the Queen Mary goes back and forth constantly between England and NY (again this might be suspended for covid, I don’t know).
There might still be a hydrofoil from South Florida to the Bahamas, there used to be one.
I don’t know what regular crossings there in the Pacific. There were ships that fairly regularly went up and down the west coast of America, and of course repositioning cruises to Hawaii and Asia and back during specific times of the year.
You talk about bridges. Bridges are closed during bad weather, especially high bridges. So the same weather events that cause rough seas also cause bridges to close. Ships can go around bad weather, a bridge there is no flexibility.
There used to be a train to Key West. The overseas railroad. Here’s the history.