Odd Behavior
Divers who go into bodies of water to view wildlife generally swim with a pod of seals for days until they gain their trust. That much time is required by the seals to determine whether the humans pursuing them are safe to approach.
Rather Strange Instincts
When Grayson and his diving companion came across the seals, they took measures. The speed with which they were approaching was strange. Especially when one of the seals chose to get up and personal with the divers.