While typically Pollution has always been covered under the liability section of boat insurance policies. Recently we have seen boat insurance companies providing a separate limit for Pollution/Fuel Spill coverage. Most companies do not make pollution/fuel spill coverage dependent on a covered loss, but some do. This difference is important to note.
While one market might provide a separate limit of $700,000 and does not make it a requirement to be a covered claim.
Another market might not provide a separate limit. They provide coverage within the liability limit and will increase the pollution/fuel spill to the legal limit of $800,000 if your liability limit is lower. This is not the same as having a separate limit, having a separate limit is best. This market does not make it required that it be a covered loss.
Also an interesting point regarding fuel spill coverage is that most insurance companies do not pay fines or penalties.