Goosebumps Deep Trouble by R L Stine

Billy Deep and his sister Sheena are visiting their uncle in Hawaii. While exploring the ocean, Billy discovers an unusual stone and pockets it. That night, strange things begin to happen. The stone seems to have mysterious powers—and they're growing stronger. As Billy and Sheena investigate, they uncover a dark secret about the island. Something ancient and dangerous has been awakened. Now they must find a way to stop it before the terror consumes them all. A classic Goosebumps tale of mystery and suspense that will keep young readers on the edge of their seats. Perfect for fans of spine-tingling adventures and unexpected twists.