Over the past few decades, a range of strategies and techniques has been used to monitor the sea. More recently, the role of monitoring has been expanded to include the use of autonomous underwater vehicles to perform ocean surveys. With these vehicles it is now possible for the scientist to make complex studies on topics such as the effect of metals, pesticides and nutrients on fish abundance, reproductive success and ability to feed, or on contaminants such as chemicals or biological toxins that are transported in particulate form and become incorporated into living organisms (plankton, bivalves, fishes) or become deposited in bottom sediments. The scientist or environmentalist may desire to detect hazardous substances in the ocean such as chemicals from an underwater vent or toxic algae such as red tide. Additionally, the military's detection of mines, biological, chemical or radioactive threats are also very important in the monitoring of the seas. These considerations explain today’s development of new types of autonomous underwater vehicles with integrated sampling equipment that is able to perform a wide-range of fully automated monitoring surveys over extended periods of time. These vehicles survey and monitor the sea environment in a cost-effective manner combining survey capabilities, simultaneous water sampling and environmental data gathering capacities. Included in these types are autonomous underwater gliders that have the ability to glide for long distances and are in some cases able to travel under power. There are currently four classes of underwater gliders: 1) those that use mechanical or electrical means of changing their buoyancy (i.e., drop weights, or electrical power from batteries), 2) those that use the thermal gradient of the ocean to harness the energy to change the vehicle’s buoyancy, 3) those that are able to use other means of power such as ocean wave energy, and 4) hybrid vehicles that use standard propulsion systems and glider systems. Gliders are designed for deep water where the vehicle can traverse large areas with minimal use of energy and are specifically designed for the needs of the Blue Water scientist, which require greater control over the vehicle (the free-drifting profiling Argos floats that scientists often use have no control capabilities beyond descending and rising vertically in the water column. The newest Argos float model cycles to 2000m depth every 10 days, with 4-5 year lifetimes for individual instruments)(Argos, 2008). Some of these glider AUVs have space for multiple scientific instruments and have the ability to obtain water or biological samples. Scientists who perform experiments in shallower water can also use the vehicle for short duration gliding dives or under power if one of the hybrid gliders is used.