It concerns me that people disagree with a valid means of protecting against catastrophic environmental disasters. Oh well.
Or bomb them. (Not the ship, them.) Because when a group who rules an area is doing something that, when continued, is going to cause you serious harm and diplomatic measures have failed, that's called an act of war (or the equivalent for non-state actors). If someone is committing acts of war against you, you go to war with them (and somehow I don't think this particular war will result in lots of US casualties).
This is what war is for.
You don't think they have been bombed enough? Did it work? Maybe the US learned something from the recent wars they waged and, with admirable consistency, lost.
The biggest thing the US should learn from recent wars is "do what you went there to do, then leave and don't try to engage in any nation building".
And they're still around, so no, they haven't been bombed enough. Dead people don't hold ships hostage.
You may want to read some news about the area - they are already being bombed. That is what started this whole issue in the first place, it's not likely to help end it. By and large, people who you are actively bombing are way less likely to listen to what you are shouting over the bombs.