Subject	Computer Vision and Pattern Recognition
Specific subject area	Side-scan sonar imaging for NOn-Mine-like BOttom Objects (NOMBO) and MIne-Like COntacts (MILCO) object detection.
Data format	Raw and Processed data.
Type of data	.jpg and .txt files (dataset with the captured sonar images and the respective annotation).
Data collection	The data was collected in situ using a 900–1800 kHz Marine Sonic dual frequency side-scan sonar of a Teledyne Marine Gavia Autonomous Underwater Vehicle (AUV) between 2010 and 2021. Then, all the data was carefully analyzed, and each image was annotated with the NOn-Mine-like BOttom Objects (NOMBO) and MIne-Like COntacts (MILCO) object type Bounding Box (BB) coordinates. •Year: 2010 | Images: 345 | MILCO occurrences: 22 | NOMBO occurrences: 12 •Year: 2015 | Images: 120 | MILCO occurrences: 238 | NOMBO occurrences: 175 •Year: 2017 | Images: 93 | MILCO occurrences: 28 | NOMBO occurrences: 2 •Year: 2018 | Images: 564 | MILCO occurrences: 95 | NOMBO occurrences: 46 •Year: 2021 | Images: 48 | MILCO occurrences: 49 | NOMBO occurrences: 0
Data source location	The data was collected over the years along the Portuguese coast during missions performed by the Portuguese Navy's sappers’ divers group number three (Destacamento de Mergulhadores Sapadores - DMS 3). This group is responsible for all activities related to mine warfare at sea.
Data accessibility	Repository name: Figshare All data can be accessed at the following link: https://dx.doi.org/10.6084/m9.figshare.24574879 The archive content can be publicly accessed and downloaded without needing any registration.