The need for intervention in underwater environments is significantly increasing in the last years. Possible applications include maintenance intervention in permanent observatories and offshore scenarios, and search & recovery for collecting objects of interest for different application domains like biology, fishery, or marine rescue just to name a few. Nowadays, these kind of tasks are usually solved with “work-class” ROVs that are launched from support vessels and are remotely operated by expert pilots through an umbilical communications cable and complex control interfaces. These solutions present several drawbacks. Firstly, ROVs are normally large and heavy vehicles that need significant logistics for its transportation and handling. Secondly, the complex user interfaces and control methods require skilled pilots for their use. These two facts significantly increase the cost of the applications. Moreover, the need of an umbilical cable introduces additional problems of control, or range limitation. The fatigue and high stress that users of remotely operated systems normally suffer supposes another serious drawback. All the pointed questions justify the need of more autonomous, cheap and easy- to-use solutions for underwater intervention missions, and this is the aim of the current FP7-TRIDENT project. So, in this paper an overview concerning the main research ongoing under this project will be presented and discussed.