In this Friday, December 4, 2018 photo, a half sunken cruise ship lays on its side, in the Gulf of Elefsina, west of Athens. Dozens of abandoned cargo and passenger ships lie semi-submerged or completely sunken around the Gulf of Elefsina, near Greece’s major port of Piraeus. Now authorities are beginning to remove the dilapidated ships. Some of them have been there for decades, leaking hazards like oil into the environment and creating a danger to modern shipping. One expert calls the abandoned ships “an environmental bomb”. (Photo by Thanassis Stavrakis/AP Photo)

In this handout photo provided by Warner Brothers Pictures and Village Roadshow Pictures, Tom Cruise plays Lieutenant Colonel Bill Cage, a soldier who replays his last day while trying to fight aliens, in director Doug Liman's “All You Need Is Kill”. The film is set to premiere on March 14, 2014. (Photo by David James/Warner Brothers Pictures)

A tank rolls out from a ship on a landing operation during military drills at the Black Sea coast, Crimea, Friday, September 9, 2016. Russia has deployed cruise missiles, multiple rocket launchers, tanks and its latest anti-aircraft system at massive military drills in Crimea. The drills which began across southern Russia and Crimea earlier this week and involve over 120,000 troops are some of the largest exercises Russia has held for years. (Photo by Pavel Golovkin/AP Photo)

Christopher Tubbs embraces his wife Sarah after arriving home during the homecoming of the USS Enterprise at the Norfolk Naval Station July 15, 2011 in Norfolk, Virginia. In its 184 days away from Norfolk, the USS Enterprise cruised nearly 60,000 miles while supporting operations in Afghanistan and Iraq. (Photo by Win McNamee/Getty Images)

A Funnel Web spider is pictured at the Australian Reptile Park January 23, 2006 in Sydney, Australia. The Funnel Web is one of Australia's deadliest animals, with a venom that is packed with at least 40 different toxic proteins. A bite from a Funnel Web causes massive electrical over-load in the body's nervous system. Finally, fatalities occur from either heart attack or a pulmonary oedema, where the capillaries around the lungs begin to leak fluid and the patient effectively drowns. Death can come as quickly as two hours after a bite if no medical treatment is sought. Due to advances in anti-venom, there has been no death from a Funnel Web bite in Australia since 1980. Australia is home to some of the most deadly and poisonous animals on earth. (Photo by Ian Waldie/Getty Images)

Girls practice sit-ups during gymnastics lessons at the Shanghai Yangpu Youth Amateur Athletic School in Shanghai, China, on May 4, 2016. China's sports system has been enormously successful since the country returned to the Olympic fold in 1980, culminating with the host nation topping the medals' table at the 2008 Beijing Olympics. And yet, with the Rio de Janeiro Games less than three months away, the system is beginning to break down due to the shifting demographics of a more prosperous nation. (Photo by Aly Song/Reuters)

Young cheetahs eat meat at The Cheetah Conservation Fund (CCF) center in Otjiwarongo, Namibia, on August 13, 2013. The CCF started breeding Anatolian livestock dogs to promote cheetah-friendly farming after some 10,000 big cats – the current total worldwide population – were killed or moved off farms in the 1980s. Up to 1,000 cheetahs were being killed a year, mostly by farmers who saw them as livestock killers. But the use of dogs has slashed losses for sheep and goat farmers and led to less retaliation against the vulnerable cheetah. (Photo by Jennifer Bruce/AFP Photo)

Discovered in 1952 by French bio-speleologist Henri Coiffait, the waterfall and accompanying sinkhole were fully mapped in the 1980s by the Spéléo club du Liban. The cave is also known as the "Cave of the Three Bridges." Traveling from Laklouk to Tannourine one passes the village of Balaa, and the "Three Bridges Chasm" (in French "Gouffre des Trois Ponts") is a five-minute journey into the valley below where one sees three natural bridges, rising one above the other and overhanging a chasm descending into Mount Lebanon. During the spring melt, a 90–100-metre (300–330 ft) cascade falls behind the three bridges and then down into the 250-metre (820 ft) chasm. A 1988 fluorescent dye test demonstrated that the water emerged at the spring of Dalleh in Mgharet al-Ghaouaghir.