Visualization

When they started out on the open water, a long dark shape started to follow them.  A creature like the Loch Ness monster pops out of the sea and starts to attack them.  When you think their luck can not get any worse, a second sea monster pops out.  This one looked like a dolphin, but larger with sharp teeth. The two creatures started to fight over who gets to eat the boat and the people on it.  When the creatures are fighting, the people make a get away.  

I could easily imagine this dino combat like when my grandma and my dog fought over the turkey leg last Thanksgiving. Two strange creatures biting each other while the turkey leg escapes.