1. An object detection system comprising: an image sensor configured to obtain input image data of a body of water; a processor for executing modules; a memory containing the modules, the executed modules including: an image slice extraction module configured to extract a sequence of 2-D slices from the input image data; a 3-D analysis module configured to perform a 3-D connected region analysis on the sequence of 2-D slices; an invariant feature computation module configured to compute image 3-D invariant features in the input image data; an image filter module configured to perform coarse filtering based on the image 3-D invariant features, the coarse filtering including comparing the image 3-D invariant features in the input image data to a data store of trained 3-D invariant features associated with known objects; and an image recognition module configured to perform fine recognition to identify at least one of the known objects from the data store within the input image data.