Anglo-Saxon Riddle

A Poem by RisqueKev

Anglo-Saxon Riddles are always fun to try and figure out. Here is one I made my self. Try to guess what it is. Hint: Watery.

My vehemence will cause lives
It brings families to demise
Do NOT underrate me!
Or you will not have time to flee!
From deep, deep down, my roar is not heard above
The plethora of cerulean culls slowly...
It's calm... It's calm... calm....
Avast! Here I come!
That mass cerulean blitz,
Nothing will stop my onslaught to come!
Thus may humans of wit and agile escape my berserk rake.
I challenge you; dare ye speak my name?...