Lost Dutchman's Gold MineThe Lost Dutchman's Gold Mine (also known by similar names) is, according to legend, a rich gold mine hidden in the Southwestern United States.3 min / Deep Oak Island mysteryThe Oak Island mystery refers to stories and legends about buried treasure and unexplained objects found on or near Oak Island in Nova Scotia, Canada.3 min / Deep Axeman of New OrleansThe Axeman of New Orleans was an unidentified American serial killer who was active in and around New Orleans, Louisiana between May 1918 and October 1919.3 min / Deep Beale ciphersThe Beale ciphers are a set of three ciphertexts, one of which allegedly states the location of a buried treasure of gold, silver and jewels estimated to be worth over $60 million as of January 2025.3 min / Deep Carroll A. DeeringDeering was an American five-masted commercial schooner launched in 1919 and found run aground without its crew off Cape Hatteras, North Carolina, in January 1921.3 min / Deep D. B. CooperOn November 24, 1971, an unidentified man using the alias Dan Cooper, later and better known as D.3 min / Deep D'Agapeyeff cipherThe D'Agapeyeff cipher is an unsolved cipher that appears in the first edition of Codes and Ciphers, an elementary book on cryptography published by the Russian-born English cryptographer and cartographer Alexander D'Agapeyeff in 1939.2 min / Medium Devil's FootprintsThe Devil's Footprints was a phenomenon that occurred during February 1855 around the Exe Estuary in east and south Devon, England.3 min / Deep Disappearance of Asha DegreeOn February 14, 2000, Asha Jaquilla Degree, a nine‑year‑old girl from Shelby, North Carolina, United States, disappeared after leaving her family's home during the early morning hours.3 min / Deep Disappearance of Brandon SwansonShortly after midnight on May 14, 2008, Brandon Swanson (born January 30, 1989) of Marshall, Minnesota, United States, drove his car into a ditch on his way home from celebrating the end of the spring semester with fellow students from Minnesota West Community and Technical College's Canby campus.3 min / Deep Disappearance of Brian ShafferIn the early hours of April 1, 2006, Brian Randall Shaffer, a 27‑year‑old medical student at the Ohio State University College of Medicine, disappeared in Columbus, Ohio, United States.3 min / Deep Disappearance of Frederick ValentichFrederick Valentich (, VAL-ən-tich) was an Australian pilot who disappeared while on a 125-nautical-mile (232 km) flight in a Cessna 182L light aircraft, registered VH-DSJ, over Bass Strait.3 min / Deep Disappearance of Lars MittankLars Joachim Mittank (born 9 February 1986) is a German man who disappeared on 8 July 2014, near Varna Airport in Varna, Bulgaria.3 min / Deep Disappearance of Maura MurrayOn February 9, 2004, Maura Murray, a 21‑year‑old nursing student at the University of Massachusetts Amherst, disappeared after a single‑vehicle crash on Route 112 near Woodsville, a village in the town of Haverhill, New Hampshire, United States.3 min / Deep Disappearance of the Beaumont childrenJane Nartare Beaumont (born 10 September 1956), Arnna Kathleen Beaumont (born 11 November 1958) and Grant Ellis Beaumont (born 12 July 1961), collectively referred to as the Beaumont children, were three Australian siblings who disappeared from Glenelg Beach near Adelaide, South Australia, on 26 January 1966 (Australia Day) in an unsolved disappearance case and a suspected abduction and murder.3 min / Deep Dorabella CipherThe Dorabella Cipher is an enciphered text written by composer Edward Elgar to Dora Penny, which accompanied a plaintext letter dated July 14, 1897.3 min / Deep Dyatlov Pass incidentThe Dyatlov Pass incident (Russian: Гибель тургруппы Дятлова, romanized: Gibel turgruppy Dyatlova, lit.3 min / Deep Flannan Isles LighthouseFlannan Isles Lighthouse is a lighthouse near the highest point on Eilean Mòr, one of the Flannan Isles in the Outer Hebrides off the west coast of Scotland.3 min / Deep Green children of WoolpitThe legend of the Green Children of Woolpit concerns two children of unusual skin colour who reportedly appeared in the village of Woolpit in Suffolk, England, sometime in the 12th century, possibly during the reign of King Stephen (r.3 min / Deep Hessdalen lightsThe Hessdalen lights are unidentified lights which have been observed in a 12-kilometre-long (7.5 mi) stretch of the Hessdalen valley in rural central Norway periodically since at least the 1930s.3 min / Deep Hinterkaifeck murdersOn the evening of 31 March 1922, six inhabitants of a small Bavarian farmstead, commonly referred to today as Hinterkaifeck (), were murdered by an unknown assailant.3 min / Deep Isabella Stewart Gardner Museum theftIn the early hours of March 18, 1990, 13 works of art were stolen from the Isabella Stewart Gardner Museum in Boston.3 min / Deep Isdal Woman1930–1945 – November 1970) is a placeholder name given to an unidentified woman who was found dead at Isdalen ("The Ice Valley") in Bergen, Norway, on 29 November 1970.3 min / Deep Mysteries: KryptosKryptos is a sculpture by the American artist Jim Sanborn located on the grounds of the Central Intelligence Agency (CIA) headquarters, the George Bush Center for Intelligence in Langley, Virginia.3 min / Deep Lead masks caseThe lead masks case (Portuguese: mistério das máscaras de chumbo, lit.3 min / Medium Man in the Iron MaskThe Man in the Iron Mask (French: L'Homme au Masque de Fer; died 19 November 1703) was an unidentified prisoner of state during the reign of Louis XIV of France (1643–1715).3 min / Deep Mysteries: MothmanIn American folklore, Mothman is the name given to a humanoid creature that was reportedly seen around Point Pleasant, West Virginia, from November 15, 1966, to December 15, 1967.3 min / Deep MV JoyitaMV Joyita was an American merchant vessel from which 25 passengers and crew mysteriously disappeared in the South Pacific in October 1955.3 min / Deep Ourang MedanSS Ourang Medan was a reported ghost ship and proposed urban legend of the 1940s.3 min / Deep Princes in the TowerThe Princes in the Tower refers to the mystery of the fate of the deposed English King Edward V and his younger brother Prince Richard, Duke of York, heirs to the throne of King Edward IV.3 min / Deep Roanoke ColonyThe Roanoke Colony (, ROH-ə-nohk) was the site of two attempts by Sir Walter Raleigh to found the first permanent English settlement in North America.3 min / Deep Rohonc CodexThe Rohonc Codex (Hungarian pronunciation: ) is an illustrated manuscript book by an unknown author, with a text in an unknown language and writing system, that surfaced in Hungary in the early 19th century.3 min / Deep Sodder children disappearanceEarly Christmas morning, December 25, 1945, a fire destroyed the Sodder residence in Fayetteville, West Virginia, United States.3 min / Deep Spring-heeled JackSpring-heeled Jack was an entity in English folklore of the Victorian era.3 min / Deep SS BaychimoSS Baychimo was a steel-hulled, 1,322 ton cargo steamer built in 1914 in Sweden and owned by the Hudson's Bay Company, used to trade provisions for pelts in Inuit settlements along the Victoria Island coast of the Northwest Territories of Canada.3 min / Deep Somerton ManThe Somerton Man is an unidentified man whose body was found on 1 December 1948 on the beach at Somerton Park, a suburb of Adelaide, South Australia.3 min / Deep The HumThe Hum is a persistent and invasive low-frequency humming, rumbling, or droning noise audible to many, but not all, people in an area.3 min / Deep Yuba County FiveThe Yuba County Five were young men from Yuba County, California, United States, each with mild intellectual disabilities or psychiatric conditions, who were reported missing after attending a college basketball game at California State University, Chico (also known as Chico State), on the night of February 24, 1978.3 min / Deep Zodiac KillerThe Zodiac Killer (also known by the pseudonym The Zodiac) is an unidentified serial killer who murdered at least five people in the San Francisco Bay Area between December 1968 and October 1969.3 min / Deep Dyatlov Pass incidentA winter expedition in the Ural Mountains ended with injuries that still invite theories.14 min / Medium Tamam Shud caseAn unidentified man, a scrap of Persian poetry, and one of Australia's strangest cold cases.13 min / Medium Isdal WomanA woman found in Norway with false identities, coded notes, and no confirmed name.12 min / Medium Lead masks caseTwo Brazilian technicians were discovered dead beside cryptic notes and handmade masks.10 min / Easy Hinterkaifeck murdersA remote Bavarian farm, footsteps in the snow, and a crime that was never solved.12 min / Medium Yuba County FiveFive men vanished after a basketball game, leaving behind a trail that never quite fits.14 min / Medium Roanoke ColonyEngland's early American colony vanished, leaving only a carved word behind.10 min / Easy Flannan Isles LighthouseThree lighthouse keepers disappeared from a remote Scottish station in 1900.9 min / Easy Mary CelesteA merchant ship was found drifting in the Atlantic with its crew gone.10 min / Easy KryptosA sculpture outside CIA headquarters still contains an unsolved encrypted passage.9 min / Easy Shugborough inscriptionA short sequence of letters on an English monument became a durable code puzzle.8 min / Easy Dorabella CipherComposer Edward Elgar's playful-looking cipher remains unresolved.7 min / Easy BloopA loud underwater sound sparked speculation before science found a colder explanation.7 min / Easy Green children of WoolpitMedieval villagers described two children with green skin and an unknown language.8 min / Easy Spring-heeled JackVictorian London was captivated by reports of a leaping, clawed attacker.9 min / Easy MothmanA winged figure entered American folklore after sightings near Point Pleasant.8 min / Easy Ourang MedanA ghost ship legend spread through newspapers, radio reports, and maritime rumor.7 min / Easy Zodiac KillerA serial killer taunted newspapers with letters, symbols, and partially solved ciphers.14 min / Deep Princes in the TowerTwo young heirs disappeared inside the Tower of London, altering English history.10 min / Medium Sodder children disappearanceFive children were unaccounted for after a 1945 house fire, and their family never accepted the official conclusion.11 min / Medium Isabella Stewart Gardner Museum theftThieves posing as police removed thirteen artworks from a Boston museum, leaving empty frames and unanswered questions.11 min / Medium Taos HumSome residents around Taos report a persistent low-frequency sound that instruments have struggled to pin down.8 min / Easy Hessdalen lightsUnusual lights over a Norwegian valley have drawn observers, instruments, and competing physical explanations.8 min / Easy MV JoyitaA merchant vessel was found adrift in the South Pacific in 1955 with its passengers and crew missing.9 min / Medium SS BaychimoAn abandoned Arctic cargo ship survived for decades as an elusive ghost ship seen through the ice.7 min / Easy Man in the Iron MaskA guarded prisoner in seventeenth-century France became an enduring puzzle of identity and royal secrecy.9 min / Easy Rohonc CodexA small illustrated manuscript is written in a script that scholars have yet to decipher convincingly.9 min / Medium