Where is the earliest water stone I can get in Platinum?

Question

I'm in Hearthome, and I wanna evolve my Eevee. Thanks!

Answer 1

To expand on the prior answer, the earliest Water Stone in the game is definitely the Solaceon Ruins stone. You can get it without any HMs but it's hidden. Basically enter the Solaceon Ruins and then follow these exact staircases in this order:

1. Top Right
2. Bottom Left
3. Bottom Left

The Water Stone is hidden on the rock in this room. If visuals would help then here's screenshots of exactly the path to follow (screenshots are from this Water Stone guide by Guide Strats):

Answer 2

The earliest you would be able to find a water stone in Platinum would be in the Solaceon ruins, east of Solaceon Town. Use the Dowsing Machine to find it.

Source: https://bulbapedia.bulbagarden.net/wiki/Water_Stone