OK, you've certainly found the monster. Give me Knowledge: Nobility and Royalty as well.
Days pass as you sail about until you've found where you're certain this Dragon Turtle must live. You begin dropping meat, a bloody haunch at a time. (1d20+15)[21] (Turtle hide check) (1d20+10)[13] (Half-elf scout's spot check)
After a few hours, you feel something surfacing below the boat
(If you bought a longship or your stronghold IS a boat, tell me now, I'm about to roll for capsize)