Planet Earth is mostly ocean. Water covers over 70% of the planet’s surface. The seas harbour incredible wildlife, provide food for billions and help balance our climate.

Yet only a tiny fraction of the ocean is protected. To keep them healthy, we need a global network of ocean sanctuaries. These will help protect oceans from overfishing, oil drilling and plastic pollution.

It is clear that we urgently need to do much more to protect our oceans. Creating ocean sanctuaries – like national parks at sea – is essential.

You think of the oceans as limitless, full of fish and able to cope with whatever we throw at them. Yet, we know very little about the oceans – we have studied the surface of Mars in more detail than the oceans.

And just because you can not see much of what happens beneath the waves does not mean our activities are not having an impact.

Far from it – the oceans are changing and their health is in rapid decline. Many fish species are on the point of collapse.

Marine environments are devastated by oil spills while deep-sea mining threatens fragile life in the depths.

Many types of pollution inevitably make their way into the ocean – we have only just woken up to the problems of plastic pollution on marine life.

As well as struggling with these problems, oceans are being hit very hard by climate change. As our planet warms, they have absorbed a lot of the excess heat but this means the oceans themselves are warming.

Sea water has also sucked up extra carbon dioxide from the atmosphere which is making the water more acidic. Both of these changes are hitting marine life hard.

We need to protect at least 30% of our oceans by 2030 to halt their decline, so we need to act fast.

This is a golden opportunity to repair the damage we have done to the oceans.

Given how much we depend on our oceans, it is an opportunity we need to take.