Warren the 13th and the thirteen-year curse / written by Tania del Rio ; illustrated & designed by Will Staehle.

Enhanced descriptions from Syndetics:

At the end of the second book in the Warren the 13th series, the Warren Hotel had transformed into a giant ship and set sail for the open seas! When Warren the 13th and the 13-Year Curse opens, Warren is adjusting to the demands of running a floating hotel and is planning his 13th birthday party when disaster strikes--the hotel is shipwrecked on a strange island. To make matters worse, his octopus-like friend Sketchy is kidnapped by a traveling circus! Warren and his friends must solve a series of riddles to find the next location of the circus and rescue their friend before it's too late. Along the way, they meet a delightful new cast of characters, including elderly pirates, a sea witch, a talking clam, and a giant sea monster. As Warren pursues Sketchy's kidnappers, he will learn the truth of his friend's mysterious origins--as well as one final secret of the Warren Hotel.