The five scientists are taken to a mystery location in the Mediterranean. Their first challenge is to determine their latitude and longitude and thus pinpoint exactly where they are. They are also asked to create insect repellent and a radio.

The team turn their attention to communication in the third episode from Carriacou. Kate challenges them to build a transmitter and radio reciever to send messages across the island, plus a kite and an accurate clock using only basic materials.

Keeping cool is the focus of the latest batch of scientific challenges. Using only the basic equipment provided, plus whatever plants they can find on the island, the team are given the task of devising a refrigeration device, and a thermometer for measuring the results.

The Rough Scientists are challenged to devise an underwater lighting system to help them explore the waters around Carriacou - but they can only use natural power sources.

With the team about to leave their tropical island base, it's time for a party. The team face the challenge of creating a light-and-sound show to celebrate their success in the previous challenges - but will this one prove too tricky even for them?