Readers could be forgiven for wondering exactly what the ocean phenomenon was that raised Bermuda’s sea levels just in time for torrential rains.

A warm-water eddy is not an uncommon visitor to local waters, according to Bill Curry, president and CEO of the Bermuda Institute of Ocean Sciences.

“If it’s a warm eddy, it will be circulating in a clockwise direction, and the water in the middle of it will raise up by a matter of tens of centimetres,” Dr Curry said.

According to the Bermuda Weather Service, yesterday’s high tides were 30cm higher than usual because of the eddy’s influence.

It made all the difference for problem areas such as the environs of Pembroke Canal: a valve in the sluice where the waterway meets the sea held back the high tides, but also kept the canal from draining until the seas dropped.

Eddies spin off from larger systems such as the warm Gulf Stream current, Dr Curry explained, and can be large: 50 to 100 kilometres across.

They are generally more common and more active to Bermuda’s north, closer to the Gulf Stream.

Cold-water eddies circulate in the opposite direction, Dr Curry said.

Instead of bulging, they bow downward at the centre, creating a depression in the ocean’s surface.