The methods of data collection, processing, and assessment of the quality of the results of a survey conducted at the Southern Ionian Sea off the Messinian Peninsula, Greece are presented. Data were collected by the GEBCO-Nippon Foundation Alumni Team, competing in the Shell Ocean Discovery XPRIZE, during the Final Round of the competition. Data acquisition was conducted by the means of unmanned vehicles only. The mapping system was composed of a single deep water AUV (Autonomous Underwater Vehicle), equipped with a high-resolution synthetic aperture sonar HISAS 1032 and multibeam echosounder EM 2040, partnered with a USV (Unmanned Surface Vessel). The USV provided positioning data as well as mapping the seafloor from the surface, using a hull-mounted multibeam echosounder EM 304. Bathymetry and imagery data were collected for 24 h and then processed for 48 h, with the extensive use of cloud technology and automatic data processing. Finally, all datasets were combined to generate a 5-m resolution bathymetric surface, as an example of the deep-water mapping capabilities of the unmanned vehicles’ cooperation and their sensors’ integration.

The GEBCO-NF Alumni Team is one of the five teams who completed the final round of the Shell Ocean Discovery XPRIZE challenge. This international team is made up of industry experts, advisors from within the GEBCO community and broader ocean community and is led by alumni from the Nippon Foundation / GEBCO Graduate Certificate Ocean Mapping Training Program at the Centre for Coastal and Ocean Mapping / Joint Hydrographic Center (CCOM/JHC) of the University of New Hampshire. The Team is distinguished by its extraordinary diversity with a global distribution of representatives from academic institutions, offshore survey and technology industries, academia as well as national hydrographic offices. The alumni worked closely with partners such as Hushcraft Ltd., Ocean Floor Geophysics Inc., Earth Analytic and Teledyne CARIS as well as equipment supplier Kongsberg Maritime AS to develop and advance the Team concept created for the Shell Ocean Discovery XPRIZE. The project was established and supervised at the University of New Hampshire.The Shell Ocean Discovery XPRIZE competition aimed to push the boundaries of ocean technologies by creating solutions to the grand challenge of mapping our ocean floor. The competition requirements had to be met within a short timeline of approximately one year per round. The Round 2 final field test was to demonstrate a complete system that could map 250 km ² in 24 hours to produce a grid with 5 m cell size and at least 10 images of the sea floor. Operations had to be remotely coordinated from a land-based operation center. The entire mapping system had to fit into a standard 40-foot shipping container.The aim of the GEBCO-NF Alumni Team has been to leverage existing technology, wherever possible, and to integrate them to achieve the competition requirements. The strategic approach is to develop strong partnerships with technology and services providers to augment the hardware, integration and software needs of the Team.The GEBCO-NF Alumni Team conceived a two-system, Autonomous Underwater Vehicle (AUV) and Remote-controlled or Unmanned Surface Vehicle (USV), concept to autonomously map the seafloor in a wide variety of ocean environments. Autonomous seafloor surveys, with remote AUV launch and recovery (human-in-the-loop) and with the USV autonomously tracking the AUV for a complete survey mission while being monitored from a remote shore station, were demonstrated to be a viable option for future offshore survey and inspection projects during Round 1.SEA-KIT, the Team’s USV, is an innovative new vessel that allows for autonomous management of AUV deployment and retrieval. In addition, the capability of being a stand-alone mapping platform was demonstrated during the competition using Kongsberg Maritime’s deep-water multibeam sonar EM304 mounted on the gondola below SEA-KIT.The Kongsberg Maritime HUGIN AUV was used for this competition to execute the underwater operations. The Team was confident that competition criteria could be met by overcoming the surface challenges of delivering an AUV to a deep-water location for mapping, coupled to the proven abilities of the HUGIN.During Round 2 Field Test, the team demonstrated automated and remote processing using a cloud-based hosting environment. End users (judges) were able to consume the GEBCO-NF Alumni Team information rapidly and efficiently.The technology, processes and procedures developed for this project are a big step towards larger scale implementation of these concepts. This development of new and innovative technologies that increase the efficiency of seafloor mapping is the Team’s contribution towards helping meet the ambitious goals of the Nippon Foundation—GEBCO Seabed 2030 Project.

The accuracy of multibeam echosounder bathymetric measurement depends on the accuracy of the data of the sound speed layers within the water column. This is necessary for the correct modeling of ray bending. It is assumed that the sound speed layers are horizontal and static, according to the sound speed profile traditionally used in the depth calculation. In fact, the boundaries between varying water masses can be curved and oscillate. It is difficult to assess the parameters of these movements based on the sparse sampling of sound velocity profiles (SVP) collected through a survey; thus, alternative or augmented methods are needed to obtain information about water mass stratification for the time of a particular ping or a series of pings. The process of water column data collection and analysis is presented in this paper. The proposed method updates the sound speed profile by the automated detection of varying water mass boundaries, giving the option to adjust the SVP for each beam separately. This can increase the overall accuracy of a bathymetric survey and provide additional oceanographic data about the study area.

The paper presents the impact that the XPRIZE Foundation competition, the Shell Ocean Discovery XPRIZE, has had on the development of current ocean mapping possibilities. A race for the prize has accelerated the development of innovative seabed mapping approaches that concentrated on new systems engineering or cutting-edge and innovative methods of existing equipment exploitation. The GEBCO - Nippon Foundation (NF) Alumni Team’s entry is presented in details as a state of the art example of mature and robust oceanmapping solution utilizing a high degree of autonomy and providing the possibilities of deepocean mapping that were unattainable before.