The largest ocean is the Pacific Ocean, and it is also the oldest. This is not a coincidence. Oceans are created by the formation of a spreading center (or "mid-ocean ridge") that creates mountains and pushes the edges of the spreading center outward. The older the ocean, the more time the earth has spent pushing the edges of the initial basin outwards, and thus the oldest oceans are the largest. In the case of the Pacific, the Eastern Pacific (off our coast) is subducting beneath North and South America, creating volcanoes (as in the Cascade and Andes mountain ranges). In the Western Pacific the ocean crust is pushing westward, and thus the Western Pacific is the oldest part of the seafloor.

The coldest seawater temperature measured in the Arctic and Antarctic Oceans is -2°C — below freezing! Seawater does not freeze at 0°C (32 F) because it contains salt. Even colder temperatures are found in salty pockets of water trapped in polar sea ice — down to -20°C.

Yes, there are many kinds of underwater currents. Most currents close to shore are caused by waves and wind. In deeper water, tides are responsible for most of the water motion. In fact, the last time I dove to the bottom of the ocean (2200 meters) in a submarine, we almost couldn’t make headway against the fast tidal currents. That means the currents were going about 2 knots (about 1 meter per second)! That’s a pretty fast current in the deep sea.

Seawater itself does not freeze until it cools to -2°C because of the salt it contains. So in the vast majority of the world’s oceans, including off the coast of Washington, sea creatures do not have to worry about getting too cold. Where seawater does freeze — in the Arctic and Antarctic Oceans — sea ice forms. Sea ice grows to a thickness of about 2-3 meters, so below the ice there is still plenty of cold, liquid water for sea creatures to live in. And above the ice polar bears and penguins can be found wandering about. Inside the ice itself there are small pockets of liquid water that host thriving communities of bacteria and microscopic plants. No life can grow inside of solid ice however.