The geography of the Darién Gap on the Colombian side is dominated primarily by the river delta of the Atrato River, which creates a flat marshland at least 80 km (50 miles) wide, half of this being swampland. The Panamanian side, in sharp contrast, is a mountainous rain forest, with terrain reaching from 60 m (200 ft MSL) in the valley floors to 1845 m (5900 ft MSL) at the tallest peaks (Cerro Tacarcuna).
The Pan-American Highway is a system of roads measuring about 26,000 km (16,000 miles) long that crosses through the entirety of North, Central, and South America, with the sole exception of the Darién Gap. On the Colombian side, the highway terminates at about 27 km (17 miles) west of Barranquillita, at Lomas Aisiadas (Casa 40) located at . On the Panamanian side, the road terminus is the town of Yaviza at . This marks a straight-line separation of about 100 km (62 statute miles). In between is marshland and forest.
For decades, efforts have been made to remedy this missing link in the Pan-American highway. Planning efforts began in 1971 with the help of U.S. funding, but was halted in 1974 after complaints by environmentalists. Another effort to build the road began in 1992, but by 1994 a United Nations agency revealed that it would cause extensive environmental damage. There is evidence in favor of the argument that the Darién Gap has prevented the spread of diseased cattle into Central and North America, which have not seen foot and mouth disease since 1954, and at least since the 1970s this has been a substantial factor in preventing a road link through Darién Gap. Embera-Wounaan and Kuna Indians have also expressed concern that the road would bring about the potential erosion of their cultures.
A United States Department of Defense Joint Operations Graphic chart published in 1995, as well as Expedia World Maps, show a road under construction linking Yaviza via a western route along the Pacific Colombian coast. It is unclear whether this road is a real feature or not.
As of April 2004 there was no apparent active construction of a road beyond Yaviza, although some improvements to the road as far as Yaviza appeared to be in progress.
The Darién National Park covers around 5,790 square kilometres of land and was established in 1980. It is the largest national park in Central America.
The first post-Colonial expedition to the Darien was the Marsh Darien Expedition in 1924/25, supported by several major sponsors including the Smithsonian. The gap itself was first traversed by the Land Rover La Cucaracha Cariñosa (The Affectionate Cockroach) and a Jeep of the Trans-Darién Expedition 1959-60, crewed by Amado Araúz (Panama), his wife Reina Torres de Araúz, the late former SAS man Richard E. Bevir (UK), and engineer Terence John Whitfield (Australia). They left Chepo, Panama on 2 February 1960 and reached Quibdó, Colombia on 17 June 1960, averaging 201 m (220 yd) per hour over 136 days. They traveled a great deal of the distance up the vast Atrato River.
In December 1960 on a motorcycle trip from Alaska to Argentina Danny Liska transited the Darien Gap from Panama to Colombia. On the trip across the Gap, Liska was forced to abandon his motorcycle and proceed by boat and foot.
A Range Rover on the British Trans-Americas Expedition in 1972 led by John Blashford-Snell is claimed to be the first vehicle-based expedition to traverse both American continents north-to-south through the Darién Gap. However, this expedition used boats to bypass the Atrato Swamp in Colombia which lies on the 'direct' Trans-Americas route and received substantial support from the British Army. "The Hundred Days Of Darien", a book written by Russell Braddon in 1974, chronicles this expedition.
The first true overland Trans-Americas Expedition was that of British cyclist Ian Hibell who rode from Cape Horn to Alaska between 1971 and 1973. Hibell took the 'direct' overland south-to-north route including an overland crossing of the Atrato Swamp in Colombia. Hibell completed his crossing accompanied by two other cycling companions who had ridden with him from Cape Horn, but neither of these continued with Hibell on to Alaska. Hibell's 'Cape Horn to Alaska' expedition forms part of his 1984 book Into the Remote Places.
The first motorcycle crossing was by Robert L. Webb in March 1975. Another four wheel drive crossing was in 1978-1979 by Mark A Smith and his team. Smith and his team drove the 400 km (250 mile) stretch of the gap in 30 days using five stock Jeep CJ-7s. They traveled many miles up the Atrato River via barges. Mark Smith has released his book Driven by a Dream, which documents the crossing. The first all-land auto crossing was in 1985-1987 by Loren Upton in a CJ-5 Jeep, 741 days to travel all on land. This crossing is documented in the 1992 Guinness Book of Records. In addition Upton returned in 1995 and became the first to drive a motorcycle, a two-wheel drive Rokon motorcycle, all on land through the Darien Gap, 49 days.
Most crossings of the Darien Gap region have been from Panama to Colombia. In July 1961, three college students crossed from the Bay of San Miguel to Puerto Obaldia on the Gulf of Parita (near Colombia) and ultimately to Mulatupu in what was then known as San Blas and now identified as Kuna Yala. The trip across the Darien was by Banana Boat, piraqua and foot via the Rio Turia (La Palma and El Real de Santa Maria), Rio Chucunaque (Yaviza), Rio Tuquesa (Chaua's (General Choco Chief) Trading Post - Choco Indian village) and Serrania del Darien.
In 1985, Project Raleigh, which evolved from Project Drake in 1984 and in 1989 became Raleigh International, sponsored an expedition which also crossed the Darien coast to coast.. Their path was similar to the 1961 above, though in reverse. The expedition started in The Bay of Caledonia at the Serrania del Darien and followed the Rio Membrillo ultimately to the Rio Chucunaque and Yaviza. Roughly following the route followed by Balboa in 1513.
Erik Jorgensen from the United States crossed in December 2005.
The Darién Gap is subject to the presence and activities of three Colombian rebel groups. These include the United Self-Defense Forces of Colombia (AUC), a right-wing paramilitary group formerly headed by Carlos Castaño; and both left-wing National Liberation Army (ELN) and Revolutionary Armed Forces of Colombia (FARC). All three groups have committed human rights violations . The U.S. State Department reported that combined, the ELN and FARC have been responsible for 51 kidnappings and ten murders of U.S. citizens. Kidnappings are common for political and financial gain. The AUC has allegedly helped Darién Gap travelers in isolated instances.
Among the political victims of the Darién Gap were three missionaries who disappeared from Pucuro on the Panamanian side in 1993. British travelers were kidnapped in Darién Gap in 2000 and held for nine months, this is documented in the book The Cloud Garden by Tom Hart Dyke and Paul Winder. In 2003, Robert Young Pelton, on assignment for National Geographic, and two teammates were detained by AUC rebels for one week in a highly publicized incident.