Ocean is a large body of salt water covering more than 70% of the Earth’s surface. It has been part of human history for thousands of years and continues to be a source of energy (for instance, through wind power and ocean thermal energy conversion), transporting people and goods around the world, supplying half of the oxygen in the planet’s atmosphere, regulating the climate by taking heat from the Equator and releasing it at the poles, and providing food for us humans as we sail the seven seas.
The ocean is divided into zones based on physical and biological conditions. For example, the photic zone includes water from the surface to 1% of the light depth where photosynthesis takes place. This is the most biodiverse area of the ocean and produces half of all oxygen on the Earth.
On the other hand, the twilight zone contains the cold, dark waters of the deep ocean. This layer is characterized by dramatic changes in salinity and temperature, which produce an effect called a halocline or pycnocline. These zones play a role in the global circulation of the ocean by separating less dense surface waters from denser, colder deeper waters.
The main source of oxygen in the ocean is phytoplankton, tiny algae that live in the photic zone. They use the sunlight, water, and carbon dioxide to produce organic material through photosynthesis. The resulting ocean productivity is measured by satellite measurements of chlorophyll. Long term composite satellite images of the ocean show regions of high productivity in yellow and green colors, while areas of low productivity appear blue.
Although the ocean is not always clear, it usually has a blue color. This is because the water molecules and the tiny particles that make up the water preferentially scatter blue light, while red and other wavelengths are absorbed. This is also why the sky is blue.
The ocean is the largest living organism and has a number of impressive features, including great diversity of life and extremes in temperature and pressure. It is also an important part of the Earth’s water cycle, storing 50 times more carbon than the atmosphere and supplying half of the oxygen on the planet.
People have been drawn to the seas throughout human history, using them for navigation and exploration, naval warfare and travel, fishing and whaling, recreational boating and sailing, leisure activities such as cruising and diving, and commercial fishing and shipping. These activities have many positive influences on marine environments and habitats, but they also have a number of negative effects including marine pollution, overfishing and ocean acidification. This is especially true if we are not careful of the consequences of our actions on the world’s oceans. The pleasure of living on board far outweighs the cons of course – as long as you don’t mind a salty hair or two, being disconnected from the outside world for weeks at a time, or having your car corrode in the salty coastal air.