[AdamLein]

What does "dangerous" mean? "Most expected damage, given the event occurs?" In that case I'd have to say that "sun explodes" is the most dangerous. "Most likely to occur?" In which case I'd have to go with chafe, or maybe corrosion.

Other than the political bits, the real problem with the poll is that it's too ambiguous. Pirates aren't a danger: just don't sail in pirate-infested waters. Collisions with shipping aren't a danger: post a lookout at all times. In order for the question to be meaningful, you need to specify the capabilities of crew and vessel, route taken, schedule, etc.