Oil in ships around European shores was 12.9 million barrels on average in May, accounting for 26 percent of all global floating storage, and more than Asia-Pacific's 9.7 million barrels of oil stored, according to estimates by oil analytics company Vortexa, as carried by Reuters.

In the two preceding months, March and April, the share of oil in floating storage in Europe accounted for 10 percent of the global storage, compared to 40 percent stored in the Asia-Pacific region. But in May, the volumes of oil held in Europe—including in the Mediterranean—exceeded the oil held off the Asia Pacific coasts for the first time since at least early 2015, according to Vortexa.