Sunk! - Fleur Hitchcock

Sun, Sea . . . and deckchairs out for revenge? Welcome to Bywater-by-Sea! Inspectors from the "Best Beach in Britain" award are in Bywater-by-Sea and the new mayor Mr Quint wants to keep the town at the top of the holiday rankings. But a holiday maker is trapped by an angry deckchair. Then a small child is chased by a pedalo, and a woman attacked by a beach umbrella.
Tom, Eric and Jacob realise that the meteorite dust has affected every item of holiday paraphernalia, and that it now appears to be increasingly determined to take revenge on the humans, local or visitor. With Grandma's help and to Tilly's disgust, the boys set out to make the town safe and track down every last piece of rebellious beach equipment without revealing their powers to anyone.