This data-set is recorded with a stereo camera in an underwater housing - the videos provide only the left image, i.e., the data is as if it would have been just recorded with a monocular camera.

The videos show different objects in form of 
(1) three paving tiles with different amounts of cracks, which are the objects of interest
(2) a construction brick with holes, which can be used to test for false positives

The data was recorded in the context of the FloodEvac project; see, e.g.:

Christian A. Mueller, Tobias Fromm, Heiko Buelow, Andreas Birk, Maximilian Garsch, Norbert Gebbeken.Robotic Bridge Inspection Within Strategic Flood Evacuation Planning. IEEE Oceans. Aberdeen, UK, IEEE Press, 2017

Maik Benndorf, Maximilian Garsch, Christian Atanas Mueller, Tobias Fromm, Thomas Haenselmann, Norbert Gebbeken, Tomasz Luczynski, Andreas Birk. Robotic Bridge Statics Assessment Within Strategic Flood Evacuation Planning Using Low-Cost Sensors. IEEE Symposium on Safety, Security and Rescue Robotics (SSRR). Shanghai, China. 2017