Under the Water, Tales from the Hidden Valley 4

 Hidden in a remote place surrounded by high mountains, there lies a secret valley. There is an entrance, but you could pass by it a hundred times and still not see it... It's finally summer, and our friends from the hidden valley are gearing up for a dreamy summer afternoon! When a new, watery friend appears, Ticky, Mister Cold and the rest of the pals explore an exciting new undewater world. But a great monster lurks beneath the surface, and our joyous friends sure are causing quite a fuss! Will they be able to escape its terrible jaws?

Review: "Returning residents of the valley are joined by an azure swamp mermaid, slumbering giant, and a night of friendship, fun, and fireworks that lights up the brilliantly hued summer sky."
-Foreword

"Porta brings the ungainly charm of his three previous seasonally themed Hidden Valley outings to this (probable) closer, filling out the ensemble cast with further unconventional characters and leaving Aqua, Olivier, the dragon, and all the rest gathered at a festive banquet beneath moonlit trees."
-Kirkus Reviews