Ocean Terror achievement in Maneater

You'll have play till you reach LVL 30. After reaching LVL 30 fast travel to any of the grottos and then the achievement should pop any where to 15 to 30 seconds after.

I found one of the fastest ways to LVL up is going after the bounty hunters plus its fun as hell.

Ps thank for the update @Tyuri2 that this may be story related and some may achieve this before lvl 30