Researchers were hoping to find wreckage from aviator Amelia Earhart's final flight, but the $2.2 million expedition had no luck.

The group leading the search, The International Group for Historic Aircraft Recovery (TIGHAR), is on its way back to Hawaii without the dramatic, conclusive plane images they were hoping to attain, according to the Associated Press.

The group still believes that Earhart and her navigator crashed onto a reef off a remote island in the Pacific Ocean 75 years ago this month.

"This is just sort of the way things are in this world," TIGHAR president Pat Thrasher said. "It's not like an Indiana Jones flick where you go through a door and there it is. It's not like that - it's never like that."

Thrasher said the group collected a significant amount of video and sonar data, which searchers will pore over on the return voyage to Hawaii this week and afterward to look for things that may be tough to see at first glance.

The group is also planning a voyage for next year to scour the land where it's believed Earhart survived a short while after the crash, Thrasher said. The group's thesis is that Earhart and navigator Fred Noonan landed on a reef near the Kiribati atoll of Nikumaroro.

Ric Gillespie, Thrasher's husband, posted updates about the trip on the group's website. "The updates tell of a search that was cut short because of treacherous underwater terrain and repeated, unexpected equipment mishaps that caused delays and left the group with only five days of search time rather than 10, as originally planned," wrote the Associated Press.

Thrasher said the environment was tougher to navigate than searchers expected.

The U.S. State Department had encouraged the privately-funded voyage, which launched earlier this month from Honolulu using 30,000 pounds in specialized equipment and a University of Hawaii ship normally used for ocean research.

An image of a Lockheed Vega 5b is currently on Google's homepage to celebrate the 115th anniversary of the birthday of Earhart. She was born in Kansas on July 24, 1897.

Earhart flew the plane from Newfoundland in Canada to Culmore in Northern Ireland to become the first woman to fly solo across the Atlantic in 1932.

She became as famous for her disappearance in 1937 over the Pacific Ocean near Howland Island as she tried to circumnavigate the world, reported The Guardian. No traces of her or her aircraft, a Lockheed Model 10 Electra, were found.