They're called pleasure boats or pleasure crafts, but, let's face it, sometimes they're a "pain." They can be an expensive habit, to say the least - and potential danger comes with the pleasure. 
They are, after your house(s) and maybe your car(s), probably your most valued assets. You can choose to own and operate a boat, yacht or Jet Ski without insurance (although some marinas and yacht clubs won't let you dock your craft unless you have coverage). That wouldn't be a very smart choice, however.
Note. If you have a homeowners insurance policy, you may have some coverage for your watercraft, but it is very, very minimal. A typical homeowners policy will pay as much as $1,000 to repair damage to your boat, but - guess what? - that damage has to occur while the boat is at your home. This is not exactly the kind of damage coverage you need. In addition, there may be some liability coverage. Some, but hardly enough.
You can gamble and not buy insurance for your watercraft, but it is a big gamble. You're risking not only losing or severely damaging the boat in an accident without compensation, but possibly your other assets if your boat causes damage and/or injuries to other boats and/or boaters.
To learn more about boat insurance, visit our Learning Center.