Floating storage of crude oil is at a six-year high, according to the International Energy Agency (IEA).

But the storage play appears less about good economics for trading firms than the lack of onshore capacity.

The IEA’s monthly oil market report estimated 95 million barrels — enough to fill 48 VLCCs — was afloat on the oceans at the end of June, an increase of one million barrels from the previous month.