Two giant gas tankers performed u-turns just miles from the Panama Canal, where months of low rainfall is snarling traffic and bringing chaos to the vital waterway.

The Pyxis Pioneer and the Sunny Bright, which between them can transport roughly 158,000 cubic meters of liquefied petroleum gas, both got to within about 10 miles (16 kilometers) of the canal in recent days before sailing away, according to ship-tracking data compiled by Bloomberg. It’s not certain where they were headed, but the biggest LPG exporters in the region are producers in the US Gulf.

The Panama Canal doesn’t have enough water. A lack of rainfall, blamed on climate change, is leading to a steady decline in levels in the Gatun Lake that feeds the conduit. The problem is so bad that increasingly stringent quotas are being imposed on how many ships can pass through it. That’s threatening trade in energy, consumer goods and food as carriers are forced to sail thousands of extra miles to make deliveries.

The Pyxis Pioneer and the Sunny Bright were empty, having delivered cargoes to customers in Asia.

While it’s not unheard of for gas carriers to avoid the canal, the two ships went all the way across the Pacific Ocean, before turning away only when they had reached the mouth of the waterway, the tracking data show.

One is signaling Houston, suggesting that it will sail south and around the southern tip of the Americas. Vessels can go around the continent, or via the Strait of Magellan which is a slightly shorter route, two shipbrokers said.

The other ship headed in the same direction before veering west. Its destination now shows as “waiting for orders,” meaning the crew is waiting to be told where to head next.

LPG has become a boom trade for the canal in recent times, helping American producers to speed up deliveries to customers in Asia. One shipper recently paid a record $2.85 million at an auction to get a carrier through the waterway promptly.