We examine several problems and solutions that use active sensing and Autonomous Underwater Vehicles (AUVs). We are particularly interested in the multiple vehicles approaches or possibilities.We discuss and formulate different types of problems. These types are then classified in an original fashion, using activities (i.e., functionalities). Various limitations exist when using AUVs and underwater technologies to tackle the kinds of problems considered. We consider not only sampling issues and communication restrictions but also motion and sensing limitations. Techniques that have been proposed are then outlined. We analyze the approach, results, advantages and disadvantages and their multiple vehicles extension(s) and/or potential.The proposed classification scheme provides an informative way for structuring sensor-based problems for AUVs. The discussions on limitations and techniques allowed the identification of a problem and technique that can benefit from an expansion to multiple vehicles.