The Secrets of Topsea series, written by Kir Fox and Shelley Coats and published by Disney Hyperion
A Friendly Town That's Almost Always by the Ocean!
”Welcome to Topsea, the strangest place you'll ever visit. In this town, the coves are bottomless and the pier has no end in sight. There's a high tide and a low tide... and a vanishing tide. Dogs are a myth, but mermaids are totally real. And seaweed is the main ingredient in every meal-watch out, it might just start chewing you back!”
The Extremely High Tide!
"Talise knows more about the ocean than any kid in Topsea. Any adult, too. As the best-and only-bathymetrist in Topsea, Talise is able to predict important things about the sea, like the next tide (Severely Low with a threat of Wildcard) or the arrival of Seaweed Season.
When Talise discovers a mysterious message in a bottle, her classmates believe it must have been sent by someone stranded on a deserted island. But Talise is convinced the message is meant for her, and it's telling her to build a boat. Everyone seems to think Talise is just being silly. All Talise knows is that she'd better finish building her boat fast, because an Extremely High Tide is coming?"