This page explains how to find Surf (TM95) - a Water-type HM Move (Hidden Move) that allows you to surf on the water to reach different locations in Pokemon Brilliant Diamond and Shining Pearl (BDSP).
Surf - Move Details
|Water||Special||90||100||15||The user attacks everyone around them by submerging them in a giant move. You can also surf on water outside of battles.||TM95|
Surf HM Location
There’s an unmissable story moment where Cynthia will ask you to travel to Celestic Town and deliver something to her grandmother. You’ll have to go to Celestic Town and defeat the Galactic Grunt hanging outside of the Ancient Ruins.
Once you do that, head inside. When you examine the paintings on the back wall, Cynthia’s grandmother will appear. She’ll take the parcel and, as a reward, will give you TM95 - Surf.
How to Use Surf
To use Surf, you must defeat Fantina, the Gym Leader of Hearthome City. She will give you the ability to do so.
You can use it by pressing the ‘A’ button close to the water and choosing to surf, or you can access it from the Pokétch app by hiting the ‘R’ button.