A mighty army of dolphins, sharks, whales, seals and gannets hunt down the billions of sardines along South Africa's east coast each winter. This is the Sardine Run: an underwater Armageddon, the greatest gathering of predators anywhere on the planet, and the most spectacular event in the world's oceans. From intimate moments of the creatures caught up in the run, to the dramatic finale of this spectacular event, The Great Tide is an action-packed feeding-frenzy, filmed underwater, on the ocean's surface, and in the air.
However, in recent years the sardine run has become less predictable, perhaps due to the warming effects of climate change. If the sardine run does not happen, the lives of the animals caught up in the drama hang in the balance. Pioneering a unique boat stabilised camera mount for surface filming, Nature's Great Events crew capture all the high octane action as the predators compete for sardines, filmed with aerial, underwater and above water cameras. Super slow motion cameras also capture the very moment gannets plunge into the water, hitting it at sixty miles an hour.
A violent winter storm is the trigger for the sardines to begin their desperate dash. They are followed by a super-pod of 5,000 dolphins and further up the coast more predators gather. A shoal of sardines 15 miles long is pushed into the shallows and aerial shots show thousands of sharks gathering to feed on them. The climax to the sardine run is a spectacular feeding frenzy as the dolphins round the sardines up into balls on which all the predators feast. Gannets rain down in their thousands, sharks pile in scattering the fish and a Bryde's whale lunges in taking great mouthfuls of sardines.

Far from land, where few of us ever venture, is the ocean beyond the boundary of any country. Largely ungoverned, wild, and lawless. Venture into the deep, dark and desolate oceans that are home to an abundance of beautiful - and downright strange - creatures.

The Indian Ocean is the third largest body of water on Earth at more than 6,000 miles wide and covering 13% of the world's surface. It is home to 5,000 species of fish, many of which only exist in the Indian Ocean. But it is also an ocean under threat from global issues such as over-fishing and climate change, which make this an ocean on the edge.

The tropical Indian Ocean is home to the Spice Islands. Characterised by beautiful sandy beaches, fringing coral reefs and coastal mangrove forests, this is a vibrant nursery area for marine life, such as whale sharks, crabs, seahorses and a great variety of fish. The coastal areas are where humans have the most direct impact on the ocean's resources.

Fly across iridescent tropical reefs, brush through a cloud of a million jellyfish, visit an alien world where the closer you look, the more you see, where the tiniest creatures support the greatest predators... We think of reefs as exotic, distant places with little or no connection to our everyday world. Yet every reef is a living city beneath the sea with a parallel existence to ours, distant yet undeniably connected. Reefs are hotspots of biodiversity as vital to life on earth as the rain-forests. They have been shaping our shorelines, literally forming islands and mountains, for millions of years. The fossil record shows that given time they have recovered from all of earth's major extinction events. Even reefs pulverised by atomic blasts at Bikini Atoll have regenerated. Yet within our lifetime reefs have come to face their greatest threat...

The sparkling blue waters of the Mediterranean Sea are home to over 700 varieties of fish and almost 10 per cent of the world's marine species. Its coastline is one of the most densely populated in the world and the human pressure on this sea is magnified each summer with the influx of holiday makers. Western civilisation developed around these shores but now human activity is having a profound effect on this endangered sea.