Route 305 is the route above Zarivar Town.
The player can Surf or fish on the water both before and after the waterfall to find some low-level water Pokémon.
It leads to Varlox Cave through use of Dive.
Route 305 is accessible from the very beginning of the player's journey but lacks any real importance aside from allowing the player to capture various Water-type Pokémon until the end of the Vesryn region. It is composed of a single body of water with a waterfall in the middle. There is also a deeper area of water in the upper parts of the lake which the player can access with Dive.
Once the player has obtained Surf, Waterfall, and Dive, they can then enter the deeper area of the lake to the north which allows them to find a cave by heading south underwater. Entering the cave and heading south leads to an area where the player can resurface, at which point they will find themselves inside of Varlox Cave.