Each of those white dots is an octopus.
Here's a closer view of one of them.
And here's the video and story behind it from NOAA's Office of National Marine Sanctuaries.
What's better than one octopus?
A THOUSAND OF THEM
While diving in the deep waters of Monterey Bay National Marine Sanctuary, researchers aboard the E/V Nautilus came across more than a THOUSAND octopuses! These octopuses – Muusoctopus robustus – were in a likely brooding posture. They were tucked into nooks in the seafloor with their arms inverted, covering their bodies and white egg clusters.
[GIF 1 description: Many white octopuses resting on the seafloor. GIF 2: An octopus rests on the seafloor and displays her siphon through her arms. GIFs/video credit: Ocean Exploration Trust/NOAA]