Live TV News Coverage of Mysterious Ocean Wake

Live TV news coverage from a news helicopter over a city harbor. Real footage, zoomed in from very far away, gimbal wobbling. A massive wake is moving under the water at impossible speed, cutting a dead straight line across the bay and throwing a wall of spray. We never see the animal, only the wake and the water bulging over whatever is beneath it. Ferries and small boats scatter out of its path. It circles a container ship once, then turns and heads back out to sea. We stay very far back and zoomed in, tracking the wake but it stays small in the frame. Overcast daylight. Appropriate newscaster commentary, alarmed and improvising.