In folklore, a mermaid is an aquatic creature with the head and upper body of a female human and the tail of a fish. Mermaids appear in the folklore of many cultures worldwide, including Europe, Latin America, Asia, and Africa.
Mermaids are sometimes associated with perilous events such as storms, shipwrecks, and drownings (cf. § Omens). In other folk traditions (or sometimes within the same traditions), they can be benevolent or beneficent, bestowing boons or falling in love with humans.
Scuba diving is an underwater diving mode where divers use breathing equipment completely independent of a surface breathing gas supply, and therefore has a limited but variable endurance. The word scuba is an acronym for "Self-Contained Underwater Breathing Apparatus" and was coined by Christian J. Lambertsen in a patent submitted in 1952. Scuba divers carry their source of breathing gas, affording them greater independence and movement than surface-supplied divers, and more time underwater than freedivers. Although compressed air is commonly used, other gas blends are also employed.
Open-circuit scuba systems discharge the breathing gas into the environment as it is exhaled and consist of one or more diving cylinders containing breathing gas at high pressure which is supplied to the diver at ambient pressure through a diving regulator. They may include additional cylinders for range extension, decompression gas or emergency breathing gas. Closed-circuit or semi-closed circuit rebreather scuba systems allow recycling of exhaled gases. The volume of gas used is reduced compared to that of open-circuit, making longer dives feasible. Rebreathers extend the time spent underwater compared to open-circuit for the same metabolic gas consumption. They produce fewer bubbles and less noise than open-circuit scuba, which makes them attractive to covert military divers to avoid detection, scientific divers to avoid disturbing marine animals, and media diver to avoid bubble interference.
The Mallows Bay–Potomac River National Marine Sanctuary is a National Marine Sanctuary in the United States located in the Potomac River in Charles County, Maryland. It is best known for the "Ghost Fleet," 118 historic shipwrecks in Mallows Bay in the sanctuary's northeast corner which is the largest shipwreck fleet in the Western Hemisphere. They are among more than 200 shipwrecks in the sanctuary, some of which date as far back as the American Revolutionary War and others to the American Civil War.
In addition to shipwrecks, the sanctuary preserves historical sites related to Native Americans, some of them as much as 12,000 years old, as well as a lengthy span of United States history, including the American Revolutionary War, the American Civil War, steamboat and steamship activity during the Industrial Revolution, and what was once an important Potomac River fishing industry. It also protects sites dating as far back as the 17th century related to African-American history, as well as an ecologically and biologically important area of the Potomac River and its Maryland shoreline that supports many species of plants and animals.
35°53′23″N 23°18′28″E / 35.8897°N 23.3078°E
The Antikythera wreck (Greek: ναυάγιο των Αντικυθήρων, romanized: navágio ton Antikythíron) is a Roman-era shipwreck dating from the second quarter of the first century BC.
Treasure hunting is the physical search for treasure. One of the most popular types of modern day treasure hunters are historic shipwreck salvors. These underwater treasure salvors try to find sunken shipwrecks and retrieve artifacts with both commercial and archaeological value. In many instances, discovery of a wreck only occurs after searching tens of thousands of square nautical miles, thus making discovery normally impossible for archaeologists.
Since the popularization of metal detectors in the 1970s, treasure hunting has also taken the form of beach combing for lost valuables. Beach hunters may search for modern jewelry, pocket change, or shipwreck treasure. Most metal detectors will fall in the $150–$600 price range, but can even cost upwards of several thousand dollars. Metal detecting is generally quite tedious and most enthusiasts go years without finding an actually valuable object. Metal detectors are quite useful to archaeologists as well. On terrestrial sites they give researchers the ability to scan large swathes of land for important artifacts without having to consume time and resources excavating large holes. Skilled amateur archaeologists are also able to assist professionals by using their metal detectors to discover previously unknown sites. For example, in the United Kingdom, many discoveries have been made by metal detectorists that have had a large impact on the understanding of early British history.
An artificial reef (AR) is a human-created freshwater or marine benthic structure.Typically built in areas with a generally featureless bottom to promote marine life, it may be intended to control erosion, protect coastal areas, block ship passage, block the use of trawling nets, support reef restoration, improve aquaculture, or enhance scuba diving and surfing. Early artificial reefs were built by the Persians and the Romans.
An opportunity artificial reef is built from objects that were intended for other purposes, such as sinking oil rigs (through the Rigs-to-Reefs program), scuttling ships, or by deploying rubble or construction debris. Shipwrecks may become artificial reefs when preserved on the seafloor. A conventional artificial reef uses materials such as concrete, which can be molded into specialized forms (e.g. reef balls). Green artificial reefs incorporate renewable and organic materials such as vegetable fibres and seashells to improve sustainability and reduce energy consumption, pollution, and greenhouse gas emissions. In some cases, artificial reefs have been developed as artworks.
An uninhabited island, desert island, or deserted island, is an island, islet or atoll which lacks permanent human population. Uninhabited islands are often depicted in films or stories about shipwrecked people, and are also used as stereotypes for the idea of "paradise". Some uninhabited islands are protected as nature reserves, and some are privately owned. Devon Island in Canada's far north is the largest uninhabited island in the world.
Small coral atolls or islands usually have no source of fresh water, but occasionally a freshwater lens can be reached with a well.
A castaway is a person who is cast adrift or ashore. While the situation usually happens after a shipwreck, some people voluntarily stay behind on a desert island, either to evade captors or the world in general. A person may also be left ashore as punishment (marooned).
The provisions and resources available to castaways may allow them to live on the island until other people arrive to take them off the island. However, such rescue missions may never happen if the person is not known to still be alive, if the fact that they are missing is unknown, or if the island is not mapped. These scenarios have given rise to the plots of numerous stories in the form of novels and film.