The Surfboard is an essential item in Temtem, as it allows you to cross water and get to areas that you otherwise could not reach. How you get it can be a little confusing, because it is mentioned so early in the game, and you even get missions and quests that seem to need it.
When you first arrive at Bircal de Mar, a town on the game’s first island, you will find a shop called Luisouvenirs. You can get a map of the Archipelago here if you show Luis a Temtem caught on the Prasine Coast. To get the map, catch any Temtem on the route to Brica de Mar. While you can ask him about a Surfboard, he tells you that he has just sold the last one.
To get a surfboard is a much more complicated process. First, you need to travel to Arissola and find Sophia’s Dojo there. Sophia is a character you meet in Brica de Mar; she is a friend of the Professor. When you arrive at the Dojo, you will be told that Sophia is not there.
To find Sophia, you will need to travel to the Windward Fort, past the Gifted Bridges, where you will find Sophia trapped in a cell. When you see her, continue towards the fort, then head to the top where you will battle Lady Lottie. Beating her will get you the Windward Key, which will then open Sophia’s cell.
Now, you can return to Arissola and fight Sophia at her Dojo. Beating her will finally get you the Surfboard, and you can now complete the missions and tasks that require it, such as the Missing Kids quest in Brica de Mar.