Hawaii is the latest in a series of island chains reaching back millions and millions of years.
The chain that is above the water now is like the latest pearl in a string that stretches back to the north-east of Russia near the Baring Straits.
As I understood it, a weak spot in the plates leads to an eruption that forms a set of islands, with the first of them being formed many millions of years ago.
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 in the sea bed – stretching like a necklace many hundreds of miles across the Pacific – recording the passage of events that have happened over millions of years.