you get it in ecruteak city dance hall after you beat the kimono girls
you dont have to surf to a gym
3rd gym
The gym in Petalburg.
I think the gym in fuschia city
After you beat the 5th gym, wally's dad will give you surf. The fifth gym is where your dad is.
the truck is by ss anne, you have to surf to get there
after you beat your father's gym
diffeat the water gym
Wally's dad who lives next to the Petalburg City gym will give you Surf once you get the badge from the gym.
The Hearthome gym leader Fantina lets you use surf in Pokemon Diamond, Pearl and Platinum.
you have to have a pokemon that knows surf(found in ecruteak city)surf to the whirl islands. then go left. the you're there
One of your Pokemon has to learn surf.