This is book number 45 in the Geronimo Stilton series.
Holey cheese, did I need a vacation I had been working my tail off at The Rodent's Gazette, so when Petunia Pretty Paws invited me to visit Whale Bay with her, of course I said yes. But our trip got off on the wrong paw, and my relaxing vacation turned into a real nightmare. That is, until Petunia and I came across a great white whale that needed our help. This would be one adventure I'd never forget