The Rising Tide

When the Jakunguh first landed on Vellikka they didn't know about The Rising Tide and saw the flat, unobstructed Yasmar Island as an excellent place to build. They quickly revised this plan when seven people were killed part way through construction by the unstoppable wave, and their well-placed buildings were torn asunder.

Manifestation

The Rising Tide is at its core a tidal wave which washes over the entirety of Yasmar Island, destroying everything in its path. There are several visual features which makes The Rising Tide stand out beyond the sheer size of it. 
The Rising Tide is recognisable as it begins to grow because of the unusual froth which forms on top of the water for a day before the wave becomes a threat to the island. The froth is a ruddy orange colour, pulled from the churned up sands and rocks on the seabed of Laykan Bay. 
With this churning up of the seabed comes a distinctly dirty acidic smell, which fills the air for miles around the bay. The acid is part mixed up debris and part dead sea creatures which have already been killed by the disruption beneath the waves.

Localization

The Rising Tide gathers in Laykan Bay before crashing down on Yasmar Island, destroying everything on the island and flooding it for several weeks following.
It occurs every four years, and there is long enough between each instance of The Rising Wave for new trees and vegetation to grow before they are once more ripped up by the roots and destroyed.

Type

Natural