Ten years since the financial crisis in Iceland, the noise of the computer servers mining for bitcoin on a former Nato airbase is many decibels louder than the vast turbines spinning away in the hydroelectric power plant down the road.

Having come through the crisis a decade ago, Iceland is now enjoying an economic revival, with technology, renewable energy and tourism replacing the unsustainable boom in banking. Visitor numbers have quadrupled and output per head is among the strongest in Europe. The employment rate is the highest in the world.

But there are fears the economy could bubble out of control once more as tourist money floods in, pushing up the value of the Icelandic króna – which is among the most volatile free-floating currencies in the world, given the tiny population behind it. The price of cod used to push the króna around even before the hot money from the banking industry arrived; now it's visitors arriving at Keflavik airport, next to the shimmering, sulphurous Blue Lagoon, that shift it.