Original: The swimming speed of Ophthalmosaurus has been estimated at 2.5 m\/s or greater, but even assuming a conservative speed of 1 m\/s, an Ophthalmosaurus would be able to dive to 600 meters and return to the surface within 20 minutes.
Simplified: The swimming speed of Ophthalmosaurus has been estimated at 2.5 metres per second or greater. Even assuming a conservative speed of 1 m\/s, an Ophthalmosaurus would be able to dive to 600 meters and return to the surface within 20 minutes.