• Currents, tides, and waves
Surface currents: large circular streams kept in motion by prevailing winds and rotation of the earth; Gulf Stream (North Atlantic), Kuroshio (North Pacific) Subsurface currents are caused by upwelling from prevailing offshore winds (Peru,  Chile) and density differences (Antarctica); the upwelling pushes up nutrients from  the ocean floor.
Tides are caused by gravitational forces of the sun and moon; there are two tides daily. Waves are caused by wind on the ocean’s surface.

Water molecules tend to move up and down in place and not move with the wave. Crest and trough, wave height and wavelength, shoreline friction
Tsunamis: destructive, fast-moving large waves caused mainly by earthquakes

• Marine life
Life zones are determined by the depth to which light can penetrate making photosynthesis possible, and by the availability of nutrients.

The bottom (benthic zone) extends from sunlit continental shelf to dark sparsely populated depths. Shallow lighted water extending over continental shelf contains 90% of marine species.

Pelagic zone: water in open oceans

Classification of marine life

Bottom-living (benthic) such as kelp and mollusks
Free-swimming (nekton) such as fish and whales
Small drifting plants and animals (plankton), which are the dominant life and food source of the ocean
The basis for most marine life is phytoplankton (plant-plankton), which carry on  photosynthesis near surface; contrast zooplankton (animal plankton).
Most deepwater life depends on rain of organic matter from above.

The densest concentration of marine life is found in surface waters, such as those off Chile, where nutrient-rich water wells up to the bright surface.