In addition to what Pete mentioned; Sunglasses and a warm, dry pair of clothes. I actually take two extra sets of clothes with me on a trip like this, one stays on land in the car and one goes into a drybag on the boat. It might just be me, but things just have a way of getting soaked.

If you're suceptable, you can start taking most sea-sickness meds the night before. Read the label to be sure, though.

Hope this helps,

Chris.