I called back and a woman answered but my called dropped so I couldn't ask who it was. I called again, it seemed as though someone had answered and then hung up right away.

6502039001 OR 16502039001 OR "650 203 9001" Free cruise. Scam? Illegal, ROBOCALL.

This is (blah blah blah, I wasn't really listening) with Royalty Cruiser on a recorded line.

they've called me 4 times, with the free crusie offer every time... any way to get them to stop?

Simply block their number on your phone.