A North Pacific female gray whale set a new record on her migration trip from Russia to Mexico and back again. This endangered species’ 14,000-mile journey took 172 days, and it is the longest recorded mammal migration on record.

The western gray whale Varvara–the Russian equivalent to Barbara–was tagged with a satellite tracking device, according to a report published by Oregon State University biologist in the journal Biology Letters. And scientists were surprised by where she and the other whales in the report swam.

Researchers did not expect the whales to travel along the eastern Asian coast to the South China Sea. Previously, researchers thought the population swam in a loop to get from the Arctic to the South China Sea.

Three of the seven tracked whales migrated to regions occupied by non-endangered gray whales. Varvara visited three major breeding areas for eastern gray whales, which are not an endangered species and are often found on the North American coast.

Mate called their migratory patterns “a genuine surprise” to most people. And the whales had researchers calling into question whether western North Pacific gray whales are still a distinct whale population or if they ever were in the past. He added that the fact that the whales interact with eastern gray whales and have such a long range “leaves a lot of questions up in the air.”

Mate proposed that the endangered western gray whales could be a group of pioneering eastern gray whales looking to regain a long migratory range that expands to Russian waters. Another possibility is that the approximate 100 western gray whales feeding near Russia are actually eastern gray whales and the western population no longer exists.

She, and the other whales, also demonstrated that western gray whales have solid navigation skills across open water, according to Mashable. She did not always stick to a coastline and her return trip to Russia did not follow her exact pathway from Russia to Mexico. On her return trip, she swam at an average of 6.5 knots, barely pausing to snack.

Varvara traveled more than 5,000 miles farther than the longest flight in the world to break the record. “Needless to say, we’re impressed,” Mate said.