Unusual visitors are making their way north.

On Saturday, a bass fisherman spotted a hammerhead shark off Monomoy, Massachusetts, and on Sunday a whale shark swam up to a fishing boat, 100 miles off Cape Cod.

The whale shark approached the The Wychmere in the middle of the night while the crew was swordfishing. The 25- to 30-foot long whale shark was probably attracted to the boat's lights.

Although the hammerhead is a shark, and the whale shark is a fish, neither species has the ability to regulate its body temperature, which is why they tend to stick to warmer waters. With ocean temperatures rising, more tropical water species are making their way north with the Gulf Stream and onto the continental shelf.