Rapids in the context of "Cataracts of the Nile"

A fall line (or fall zone) is the area where an upland region and a coastal plain meet and is especially noticeable at the place rivers cross it, with resulting rapids or waterfalls. The uplands are relatively hard crystalline basement rock, and the coastal plain is softer sedimentary rock. A fall line often will recede upstream as a river cuts out the uphill dense material, forming "c"-shaped waterfalls and exposing bedrock shoals. Due to these features, riverboats typically cannot travel any further inland without portaging, unless locks are built. The rapid change of elevation of the water and resulting energy release make the fall line a good location for water mills, grist mills, and sawmills. Seeking a head of navigation with a ready supply of water power, people have long made settlements where rivers cross a fall line.

The Philae temple complex (/ˈfaɪliː/; Ancient Greek: Φιλαί or Φιλή and Πιλάχ, Arabic: فيلة  Egyptian Arabic: [fiːlæ], Egyptian: p3-jw-rķ' or 'pA-jw-rq; Coptic: ⲡⲓⲗⲁⲕ, ⲡⲓⲗⲁⲕϩ, Coptic pronunciation: [ˈpilɑk, ˈpilɑkh]) is an island-based temple complex in the reservoir of the Aswan Low Dam, downstream of the Aswan Dam and Lake Nasser, Egypt in Africa.

Originally, the temple complex was located on Philae Island, near the expansive First Cataract of the Nile in Upper Egypt. These rapids and the surrounding area have been variously flooded since the initial construction of the Aswan Low Dam in 1902. With the construction of the modern dam in Aswan (1960–1970) a few kilometers upstream, this temple was going to face total flooding and was initially omitted from the Nubia Campaign project to rescue all temples in the area and avoid what had previously happened with the Aswan Low Dam and the Temple of Philae. However, the importance of the monumental complex, formerly known as the Pearl of the Nile, remembered for the description by Pierre Loti in his literary work Mort de Philae, led to further commitment from UNESCO member countries, which launched an international competition to save the monuments of Philae.

Portage or portaging (CA: /pɔːrˈtɑːʒ/; US: /ˈpɔːrtɪdʒ/) is the practice of carrying water craft or cargo over land, either around an obstacle in a river, or between two bodies of water. A path where items are regularly carried between bodies of water is also called a portage. The term comes from French, where porter means "to carry", as in "portable".

Early French explorers in New France and French Louisiana encountered many rapids and cascades. The Native Americans carried their canoes over land to avoid river obstacles.

The Mekong or Mekong River (UK: /miːˈkɒŋ/ mee-KONG, US: /ˌmeɪˈkɔːŋ/ may-KAWNG) is a transboundary river in East Asia and Southeast Asia. It is the world's twelfth-longest river and the third-longest in Asia with an estimated length of 4,909 km (3,050 mi) and a drainage area of 795,000 km (307,000 sq mi), discharging 475 km (114 cu mi) of water annually. From its headwaters in the Tibetan Plateau, the river runs through Southwest China (where it is officially called the Lancang River), Myanmar, Laos, Thailand, Cambodia, and southern Vietnam. The extreme seasonal variations in flow and the presence of rapids and waterfalls in the Mekong make navigation difficult, though the river remains a major trade route between Tibet and Southeast Asia. The construction of hydroelectric dams along the Mekong in the 2000s through the 2020s has caused serious problems for the river's ecosystem, including the exacerbation of drought.

A whirlpool is a body of rotating water produced by opposing currents or a current running into an obstacle. Small whirlpools form when a bath or a sink is draining. More powerful ones formed in seas or oceans may be called maelstroms (/ˈmeɪlstrɒm, -rəm/ MAYL-strom, -⁠strəm). Vortex is the proper term for a whirlpool that has a downdraft.

In narrow ocean straits with fast flowing water, whirlpools are often caused by tides. Many stories tell of ships being sucked into a maelstrom, although only smaller craft are actually in danger. Smaller whirlpools appear at river rapids and can be observed downstream of artificial structures such as weirs and dams. Large cataracts, such as Niagara Falls, produce strong whirlpools.

Aurajoki ([ˈɑu̯rɑˌjoki]; Swedish Aura å) is a river in south-western Finland. It originates in Oripää, and flows through Pöytyä, Aura, Lieto, and ultimately the city of Turku before discharging into the Archipelago Sea. The total length of the river is about 70 kilometres (43 mi), and it contains eleven rapids, the biggest of which is Nautelankoski at Lieto. The reserve tap water for Turku Region is drawn from Aurajoki, the city's secondary waterworks being situated by the Halinen rapids.

The waters of the Aurajoki are brown. Situated in an agricultural zone, the river is made turbid by surface runoff from nearby farms with eutrophication as the biggest threat. Its condition has been improving since the 1970s and Aurajoki is now clean enough to support salmon.

The St. Lawrence Seaway (French: la Voie Maritime du Saint-Laurent) is a system of rivers, locks, canals and channels in Eastern Canada and the Northern United States that permits oceangoing vessels to travel from the Atlantic Ocean to the Great Lakes of North America, as far inland as Duluth, Minnesota, at the western end of Lake Superior. The seaway is named for the St. Lawrence River, which flows straight from Lake Ontario to the Atlantic Gulf of St. Lawrence. Legally, the seaway extends from Montreal, Quebec, to Lake Erie, and includes the Welland Canal. Ships from the Atlantic Ocean are able to reach ports in all five of the Great Lakes via the Great Lakes Waterway.

The St. Lawrence River portion of the seaway is not a continuous waterway; rather, it consists of several stretches of navigable channels within the river, a number of locks, and canals along the banks of the St. Lawrence River to bypass several rapids and dams. A number of the locks are managed by the St. Lawrence Seaway Management Corporation in Canada, and others in the United States by the Great Lakes St. Lawrence Seaway Development Corporation; the two bodies together advertise the seaway as part of "Highway H₂O". The section of the river from Montreal to the Atlantic Ocean is under Canadian jurisdiction, regulated by the offices of Transport Canada in the Port of Quebec.

Whitewater forms in the context of rapids, in particular, when a river's gradient changes enough to generate so much turbulence that air is trapped within the water. This forms an unstable current that froths, making the water appear opaque and white.

The term "whitewater" also has a broader meaning, applying to any river or creek that has a significant number of rapids. The term is also used as an adjective describing boating on such rivers, such as whitewater canoeing or whitewater kayaking.