If you're ever marooned on a desert island, don't count on a message in a bottle to save you. That's because it can take over a hundred years for these objects to wash ashore, as a German woman recently discovered.
Marianne Winkler found an old bottle on a beach on Amrum Island, Germany earlier this year with a postcard from the early 1900s inside. Instructions printed on the card asked for its discoverer to mail it back to the Marine Biological Association (MBA) of the United Kingdom in the care of George Parker Bidder. The message promised a shilling in return.
"We haven't had [a bottle] returned in living memory," says Guy Baker, an MBA spokesperson. "So when this one turned up in April it was quite a surprise."
The bottle and its message were part of an experiment conducted between 1904 and 1906 by scientist and former MBA president Bidder. He dropped 1,020 weighted bottles into the southern North Sea (map) in an attempt to figure out the movement of the area's bottom currents.
Bidder got about half of his messages back, says Baker. And the longest it took for one of his bottles to come home—before this current one—was about four years. (Read about history's oldest message in a bottle.)
There are about 400 bottles unaccounted for, says Baker. "I expect all of those will have been smashed or lost forever somewhere."
Chucking objects and instruments into the ocean for scientific study is a time-honored method that's remained relatively unchanged: Although the objects dropped into the ocean have become more advanced.
Sometimes, accidental spills from container ships carrying everything from tennis shoes to rubber duckies to millions of ocean-themed Lego pieces provide an inadvertent means of tracking ocean currents. (Read about how the world's oceans are full of trash.)
Scientists have also used the debris from the 2011 Japan tsunami to better understand how water moves in the central Pacific ocean. But mostly, the objects are deliberately released into the sea.
International collaborations between universities, research institutes, and government agencies help maintain global networks of surface and deep-sea floats. The surface floats, or drifters, talk to satellites as they ride ocean currents around the world, enabling researchers to get near real-time information on the instruments' location and data on water temperature and salinity.
In Bidder's time, the most he could hope for was information on a bottle's release point and where it washed ashore. But now, scientists can see how currents change from month to month, with the seasons, and even when hurricanes whip through an area, says Renellys Perez, an oceanographer at the University of Miami and the U.S. National Oceanic and Atmospheric Administration.
Deep-sea floats in the Argo network can track ocean currents from the sea surface to 6,600 feet (2,000 meters) deep, says Nathalie Zilberman, an oceanographer at the Scripps Institution of Oceanography in San Diego.
New float designs will enable even deeper examinations of ocean currents at 19,700 feet (6,000 meters).
Return to Sender?
Unlike Bidder's bottles, floats in global networks like Argo—which contain about 3,800 floats—don't normally make it back to shore. "When they die, when the battery runs out, they just dive," says Zilberman. Many end up on the seafloor, although some run aground or wash ashore.
Each float displays a phone number people can call if they find one. The institution responsible for them can then recover the floats, Zilberman says.
There isn't often a reward for their return. But in Winkler's case, Baker says, the MBA went online to eBay and found an old shilling they were able to send to her, along with a letter of thanks.
Bidder's bottle has also been submitted to the Guinness World Records for consideration as the oldest message in a bottle ever recovered. The current record-holder is a 99-year-old bottle discovered in a fishing net off the Shetland Islands in 2013.
Follow Jane J. Lee on Twitter.