When the young British composer Ralph Vaughan Williams wrote his first symphony, he dedicated it to the sea. The choral piece has one of music's most famous opening lines, a testament to the spectacular power oceans have always held over us: "Behold, the sea itself!" Last week, people across the world were beholding the seas, but for all the wrong reasons. A diplomatic tussle was under way between the Australian government and Unesco as to whether the Great Barrier Reef, the world's largest coral reef, should be put on the UN body's list of endangered sites. Canberra argues that it is doing enough to protect the site, and that listing it would be premature and unnecessary. On the other side of the world, Britain's Royal Navy was facing accusations of irresponsibly detonating unexploded bombs in British waters, most of them from German bombing campaigns during the Second World War. Despite the government having access to more environmentally friendly means of disposing of them, the navy's more aggressive tactics are thought to be making surrounding marine life, particularly whales and dolphins, go deaf. For species that rely on hearing for navigation, the results are deadly. And in what could not have been a more dramatic reminder of the need to do more to protect the world's most important resource, a burst at an allegedly under-maintained gas pipeline in the Gulf of Mexico caused the remarkable phenomenon of an underwater fire. The situation was eventually brought under control five hours later, reportedly by using nitrogen to fight the incident at its source. While last week was particularly full of major news items, we have known about the precarious state of our oceans for some time. Less than three per cent of our seas are designated as protected and a quarter of its mammals are thought to be at some risk of extinction. The threat could be worse than currently anticipated. We still know remarkably little about oceans. While the sea covers more than 70 per cent of our planet's surface, less than 20 per cent of it has been explored. A rare certainty when it comes to the ocean is the vital role it has played supporting humans. Fish is the staple protein in the diets of one billion people, and yet the global community continues to dump eight million metric tonnes of plastic waste annually, which kills many millions of specimens of marine life each year. As a complex and enduring ecosystem, our seas have always been capable of handling a healthy degree of resource extraction by humans. Today, 350 million people rely on them for employment. Even as global populations rise, mankind can find a sustainable way of taking food, precious metals and basing tourism industries on the ocean. But to do this, today's exploitative free-for-all must stop. Not doing so would not only squander our most important resource, it would also endanger one of mankind's major tools in fighting the challenges of the future. Marine algae, for example, is being investigated for its use as an alternative fuel, as a means of saving coral, and even as a sustainable protein source. An underwater fire might make for eye-catching footage, but it is indicative of a wider neglect that is, so far, going unchecked. Any attention given to the health of our seas is welcome, but if the international community is to protect it in the long term, a deeper appreciation of its importance and vulnerability is needed.