Most of what happens at sea is out of sight, and therefore out of mind. Please spare a second thought for the oceans on World Oceans Day on June 8th. There’s hope, but we must act now.
How do we define the sea?
It is not always easy to differentiate bodies of water, but usually, an ocean has no boundaries (e.g. Pacific), and a sea is normally enclosed by land on most sides (e.g. Mediterranean Sea) and generally, a lake is surrounded by land and contains fresh water (even one as large as the Caspian Sea at 371,000 km2), but only 1% of Earth’s water is fit for drinking. The oceans contain 97% of Earth’s water and cover 71% of the planet’s surface (about 362,000,000 square kilometres / 140,000,000 square miles). The largest ocean is the Pacific, followed by the Atlantic, Indian, Southern (Antarctic) and Arctic.
What makes the sea what it is?
Planet Earth has gone through many physical changes since it formed 4.6 billion years ago, with a very hot core of metal with molten rock floating around it and a thin crust of land at the surface kept cool by a vast expanse of water. Scientists believe a solid mass of land appeared from the water which then started continually moving apart slowly through plate tectonics with the oceans moulding and shaping it, creating the continents we know today. 90% of all volcanic activity occurs in the oceans and some tectonic plates are moving apart at a rate of 15cms every year (6 inches). Mauna Kea is a dormant volcano in Hawaii rising 10,203 metres (33,474 feet) from its base on the ocean floor and it would be the highest mountain on the planet, but only 4,170 metres (13,680 feet) of it are actually above sea level. Recently, new forms of life were discovered near deep-sea hydrothermal vents along the mid-ocean ridge, which is a great mountain range almost 65,000 km (40,400 miles) long, making it the largest single feature on Earth. The new life forms included a giant tube worm that uses chemical energy, rather than light energy, and even a sulphur-based bacterium, instead of carbon like most life on Earth. Oceanographers believe that less than 5% of the ocean has been explored, but unfortunately, most of the sea exploration currently being done is by oil and gas companies in the Arctic, Great Australian Bight, etc and we all know what environmental disasters can occur, with oil tankers like the Prestige and oil rigs like the Deepwater Horizon, which is still leaking in the Mexican Gulf, believe it or not, since 2010! Anyway, an incredible 99% of the Earth’s liveable space can be found in the oceans, which is home to as much as 95% of the world’s wildlife. More than 90% of this habitat exists in the deep sea below 1800 metres, often referred to as “the abyss”, yet almost all of this has not been explored by humans due to the high water pressure. It can be more than 8 tonnes per square inch of pressure at the deepest part of the ocean called “Challenger Deep” in the Mariana Trench in the Western Pacific, near Guam. It is 10,984 metres (36,037 feet) deep, so if you turned Mount Everest’s 8,848 metres (29,029 feet) upside down, it would fit inside with more than a kilometre of water above it. Curiously, only 22 people have been to Challenger Deep, whilst 24 people claim to have been to the moon. The Great Barrier Reef, measuring more than 2,300 kilometres (1,430 miles), is the largest living structure on Earth and can even be seen from the Moon, but it is in great danger because of ocean acidification and repeated coral bleaching. Interestingly, due to the fact that salty seawater is quite good at preserving things, the world’s oceans are like a gigantic museum with more human artefacts in it than there are in all the world’s museums combined. At a conservative estimate, there are more than 3 million shipwrecks lying on the seabed.
What is in the sea (and what should not)?
The ocean is the habitat of 230,000 known species, but because so much of it is unexplored, the number of species that exist is possibly much larger, perhaps even as many as two million. The largest animal ever to live on our planet is the blue whale, which can measure up to 30 metres (98 feet) in length, weigh up to 173 tonnes, and approximately 10,000 – 25,000 currently exist. Sadly, whaling nearly caused their extinction, and that of many other species too. The smallest and rarest of the ocean mammals (Cetaceans) is the Vaquita and in 2021, only 10 are believed to still exist. The round-trip journey of a Gray whale set a new record for the longest ever mammal migration, covering more than 22,000 kilometres (13,750 miles). The sea appears blue because it is the colour least absorbed by seawater, which is also most absorbed by drifting microscopic plants, called phytoplankton, which provide more than 50% of Earth’s oxygen. It is not recommended to swallow seawater due to high levels of salt (Sodium Chloride (NaCl)), but if you did, it may also contain millions of bacteria, hundreds of thousands of phytoplankton, tens of thousands of zooplankton and, of course, manmade marine pollution too. 80% of all the pollution and contamination in the oceans comes from human activities on land (For example, dumping of refuse including plastic waste, factory waste products, radiation from nuclear reactors like Fukushima, ships cleaning out their tanks and the misuse of pesticides and herbicides in farming). Seawater freezes at a lower temperature than fresh water (about -2ºC / 28.5ºF, depending on salinity). There are many other salts, gases and solids dissolved in it, which obviously interests deep sea mining companies, including enough gold for about 4 kilos per person. The top 3 metres (10 feet) of the ocean hold as much heat as our entire atmosphere. The last time carbon dioxide (CO2, at 415ppm) levels were this high 4 million years ago, the oceans were about 20 metres higher. We know that since 1880, when Carbon Dioxide was 280ppm, there has been about 23 centimetres (9 inches) of sea level rise due to melting glaciers and polar ice caps, with 7.5 centimetres in only the last 25 years. Sadly, scientists expect this to increase rapidly this century because oceans are heating up so quickly, after passing their point of no return in 2014. They have absorbed at least 90% of the heat humanity has created from burning fossil fuels, so global warming and climate change now threaten most coastlines with coastal erosion.
How does humanity benefit from the sea?
Food: Humans consume the greatest percentage of their protein from fish (14%) and half the world’s population (3.9 billion people) depend on it, but nearly all fish stocks are suffering from unsustainable overfishing. Bottom trawling the floor of the ocean also causes the destruction of habitats and releases huge amounts of CO2, which also leads to the development of dead zones. Trawling nets also catch much more than can be sold, including dolphins, turtles and sharks, with approximately 111 million sharks brutally killed each year, some of which are used for shark fin soup (where fishermen cut off fins and tail and then throw the shark back into the water to bleed to death, or drown, as they need to swim to move water over their gills).
Protection: International Waters cover about 50% of the Earth’s surface and is virtually unprotected beyond national jurisdictions, as most countries with access to the sea claim rights to Territorial Waters up to 12 nautical miles from their coasts. Globally, only about 12.2% of Territorial Waters are protected, compared to 14.8% of global land area.
Transport and Leisure: At sea level, water is 784 times denser than air, making it much more difficult to travel by sea, and that is why we see vessels trying to get as much of their bulk out of the water as possible to reduce the drag co-efficient. Distances are described in nautical miles, which is the equivalent of 1.85 kilometres (1.15 miles). Speed at sea is defined in “knots” or nautical miles per hour (So, 10 knots = 18.5 kilometres per hour (11.5 mph)). Up until quite recently, we used boats made from wood with oars or sails to get around, but now most are made from plastic or metal equipped with engines or motors. The first round the world voyage was completed during the years 1519-1522 by the Victoria, part of Ferdinand Magellan’s attempt. The largest sailing vessel ever built is Sailing Yacht A at 142.8 metres (468.5 ft) and the fastest is the Vestas Sailrocket 2 at 65.5 knots (121kph / 75mph). Approximately 90% of the world’s trade between countries is carried by ships, particularly from China to the rest of the world. Most marine vessels need massive engines (2-stroke engines up to 107,390 horsepower) to move their large bulk, but unfortunately they also use the cheapest and most polluting marine diesel oil fuel available, making it cheaper than flying, or going by train, if you could. The largest ship ever built was the Seawise Giant, a 458.5 metre long oil tanker capable of carrying 4.1 million barrels of oil, but you need very large ports to handle that, and curiously, the world’s largest port is in Rotterdam, the Netherlands. The fastest speedboat was the Spirit of Australia in 1978 at 276 knots (511kph / 318 mph). The fastest submarine was the Soviet K-222 at 45 knots. Millions of vessels use the water every day and $3.6 billion was spent on recreational boats in the US alone in 2016.
How to Save Our Seas?
Individually: Remember that whatever ends up on the ground, ends up in the drain, which ends up in the river, which then ends up in the ocean. Make better choices to use biodegradable products with natural ingredients.
Collectively, including Governments: We must stop contamination and pollution entering the ocean in the first place and that means putting pressure on governments and corporations. That also means finding ways to reduce our waste from rubbish dumping, plastic use, artificial clothing fibres, radiation and factory farm runoff (fertilizers, pesticides, etc). We should not allow unsustainable fishing practices to continue, including overfishing with nets, as most of the plastic in the Garbage Patches is old fishing materials. We need to help vulnerable coastal communities prepare for many of the difficulties they are about to face.
Unpopular opinion: All of us share some responsibility for the mess we have created in the water on Earth through the choices we have made, products we have bought and continue to buy, so protecting it from further environmental disasters and cleaning up our mess must now be top priorities.
Disclaimer: Whilst every effort has been made to check the veracity of the information contained within, certain limitations could result in not all data being current or completely accurate. Please feel free to contact us if you feel something needs updating.
Save Our Seas Test
How it started
How it's going
SOSquiz Glossary of Terms (with links to Wikipedia)
6th mass extinction (Holocene Extinction)
AEEA (Asociación Española de Educación Ambiental)
ARPANET (Advanced Research Projects Agency Network)
Carbon Dioxide (CO2)
Carbon dioxide in Earth’s atmosphere
Carbon Monoxide (CO)
Centres for Disease Control and Prevention (CDC)
Coronavirus (Covid-19 or SARS Cov-2)
Gross Domestic Product (GDP)
Human impact on the environment
Intergovernmental Panel on Climate Change (IPCC)
Internal combustion engine (ICE)
Internet service providers (ISP)
National Security Agency (NSA)
Particulate Matter (PM 10, 2.5 & UFP)
Psychological impact of climate change
Quality of life (QOL)
Ultrafine particles (UFP)
United Nations Educational, Scientific and Cultural Organisation (UNESCO)
World Health Organization (WHO)
World Wide Fund for Nature (WWF)
World Wide Web (www)