Hawaii is the latest in a series of island chains reaching back millions of years. Hawaii is above the water, but the earlier islands are now worn away and under the sea..
A weak spot in the tectonic plates leads to an eruption that creates a group of islands. The first eruption happened millions of years ago off the coast of north-east of Russia near the Baring Straits..
Then the plate moved slowly to the south east, cutting off the source that fuelled the formation of the islands.
Over time those islands wore away until they were beneath the sea. Meanwhile, another island chain spurted out of the weak spot hundreds of miles further along the path which the plates were taking.
And now with sonic pinging, we can see the remains of these islands – bumps on the sea bed stretching like a necklace thousands of miles across the Pacific – recording the passage of events that have happened over millions of years.