Set on far north Queensland's Great Barrier Reef, this adventure series revolves around a scientific search and recovery team working for General Trust Corporation (GTC), a large Australian industrial and pastoral group. Led by Captain Ted King and his first mate and diving expert Jack Meuraki (a Thursday Islander), the team of scientists and divers are also often required to carry out missions for the government. The team is highly proactive with regard to conservation and vehemently opposed to any type of exploitation of the Reef.
The centre of operations for the team is a 135-foot windjammer named the New Endeavour. The ship also houses a sophisticated piece of electronic equipment called Minus Five (Mineral Identification Nuclear Undersea Seismography Mark V), which the Endeavour team affectionately call 'Grandma,' after the line in 'Little Red Riding Hood': 'What big eyes you have!' Specifically developed for General Trust projects, Grandma serves a number of functions, including providing accurate geological analyses of the seabed and the earth below it. Though Grandma plays a vital role in the various missions and adventures that ensue, the machine's presence must be kept secret, since GTC and the Federal Government are concerned that foreign political and commercial interests might attempt to get hold of the technology (which includes, for example, the ability to locate mineral deposits or sunken wrecks with valuable cargo).