A lurker awaits

 one hundred meters beneath the surface
The wreckage of the ship certainty settles into the mud
A monster continues to move
 It bellows far beaneath the waves

 The creature patrols and lurks
 It hides around the sunken structure
Patience older than the ocean itself
 Occasionally pale shapes pass above
 
Disappearing before the eyes can establish what it was
 The creature is centuries old it knows the shapes
 It has been there all along
 waiting for the next ship to sink