This paper describes the design and proposed control methods for a 6-legged swimming and walking robot that can be used in a variety of different transportation and equipment control applications above ground, under water and above water. Known as the TURTLE (Tele–operated Unmanned Robot for Telemetry and Legged Exploration), a prototype of this mobile robot is currently being designed and developed for experimental testing in the near future. It will be powered by rechargeable electric batteries (to be recharged by solar panels) and all of its actuators will be electric motors, each controlled and monitored by onboard microcontrollers supervised by an onboard master computer. The TURTLE will be fitted with several high-resolution digital cameras, 3D laser and sonar scanners, an IMU (Inertial Management Unit), electronic compass, GPS (satellite navigation) module, underwater sonar transceiver hardware and two or more types of long-distance wireless communications hardware. The first prototype of the TURTLE will focus on basic tasks such as remote video surveillance, 3D terrain surface scanning (above ground and underwater), basic swimming styles, basic walking styles, climbing over large rocks and walking over very rough ground and steep terrain. This paper describes the main objectives, basic performance specifications, functions and mechanical design solutions that have been developed so far for this project. It covers details of the various different swimming modes and feasible solutions for achieving the main design objectives.