i am thinking about a segment where people were on a shipboat to some exotic land...and they never made it. then i remember a scene in that segment where strange notes where found on some random island. can anyone help me?

Ironically enough I was just reading about 2 similar cases

Not sure which one you're after

http://www.unsolved.com/missing.html

look for Hawaiian fishermen or lost fishermen...2 different cases.