In recent years, small craft used for drug trafficking, smuggling, human trafficking and piracy have posed a growing threat to ocean observations and maritime traffic surveillance. In order to combat such threats, microwave radars have been widely used, for maritime surveillance and target reconnaissance tasks, due to their capabilities to operate in all weathers and day and night. However, maritime radars, and particularly those carried on aircraft (such as drones), are confronted with disturbances due to sea clutter which has a strong impact on the detection function, in particular for observations at very grazing angles. Despite that airborne maritime radars typically operate at low grazing angles, from necessity or to achieve the best detection performance, it has also become important to better understand the characteristics of clutter observed at medium and higher grazing angles to undertake maritime reconnaissance using radar embedded on drones. Thus, with a view to better control of sea clutter in a context of observation via a drone with the development of functions for detecting, locating and tracking targets present in a maritime environment, this paper offers a summary of different modelling and characterization of sea clutter in grazing to very grazing configurations.