To get Surf on Pokemon Platinum, just when you exit the tall grass near the MooMoo Milk shop on route 210, you see a group of PSYDUCKS (duck like Pokemon) grouped together. Cynthia (a girl whom you meet on the way there) gives you a Secret potion in Valor Lakefront. Use it on the secret potionon the PSYDUCKS (the group of Pokemon) and they disappear. Cynthia gives you a Old Charm to give to her Grandma in Celestic Town. After facing 10-15 trainers, you arrive at Celestic town. I Reccomend you use the HM Defog, so the fog is clearer. Go fuel up your Pokemon at Poke Center, then go to The Celestic ruins. You will see Cynthia's grandma in the ruins and start to talk to her. Then Galactic Boss (Cyrus) walks in and battles you. After beating him, Cynthia's grandma speaks to you and gives you The HM Surf , giving you access to Canalave City. THATS HOW YOU GET THE HM SURF!
In Celestic Town you have to talk to the elder. A.K.A. Cynthia's Grandmother. She doesn't look special. She just looks like an old lady.
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Surf is HM #3. :-)
Get the HM Surf then teach it to a pokemon.
beat the fifth gem leader than you get the Hm surf
The elder in Celestic Town. It's part of the plot (You need surf to get farther in the game, significantly), so it shouldn't be too hard.
The HM Whirlpool is not obtainable in Pokemon Platinum, for there is no use for it during gameplay.