From Divers to Communities: An IoT-Based Crowdsourcing Sensing Approach to Protect Underwater Heritage Sites

Underwater cultural heritage, such as ancient shipwrecks and submerged archaeological sites, faces increasing risks from climate-driven environmental changes. Salinity shifts, temperature anomalies, and biofouling contribute to the degradation of these resources [1]. This study explores deploying 12 IoT-enabled devices with a crowdsourcing strategy to monitor and address these challenges effectively. 

Three device variants are available: Type 1 features an acrylic enclosure and is deployable either from boats at depths of 2–3 meters or by divers for short-duration deployments. Type 2 uses an aluminum enclosure and is designed for long-term seabed deployments. Types 1 and 2 both measure temperature, salinity, and pressure. Type 3 is a specialized variant that replaces the pressure sensor with a chlorophyll sensor and is intended for monitoring algal concentrations. 
Each device incorporates a data logger built on a microcontroller, connected to sensors via serial interfaces such as RS485 and I2C. The microcontroller interfaces with sensors to record measurements, storing data locally until retrieval. All  devices feature a power management system with custom-designed PCBs for efficient energy use.  

Data gathered by the devices is stored locally and transferred to a cloud platform via an intuitive mobile app. Communication between the devices and the smartphone uses Bluetooth Low Energy (BLE), while data uploads to the cloud.  The application provides immediate and structured access to the data, eliminating the need for additional hardware or infrastructure and enabling seamless data availability without added operational costs. 

Community participation plays a central role in this system. Local communities deploy and retrieve boat-based sensors, improving the coverage and frequency of monitoring activities. By pooling data from various contributors, detailed information of environmental conditions near cultural heritage sites is acquired. 

The devices are subject to thorough calibration, either through controlled sensing operations or by comparison with ground-truth data acquisitions, to ensure reliable data collection. Conductivity sensors are standardized against established salinity benchmarks, temperature sensors are tested using laboratory-grade reference instruments, pressure sensors are calibrated in controlled pressure chambers, and chlorophyll sensors are validated using fluorescence reference standards. 

Field trials at four underwater sites tested the system under diverse conditions, providing a robust environment to assess device performance and crowdsourcing effectiveness. Feedback from divers, local participants, and heritage professionals refined functionality. Adjustments included stronger enclosures, improved BLE connection stability and an enhanced mobile app interface. 

This study demonstrates the potential of combining smart sensor technology with community engagement to protect underwater heritage. Leveraging IoT devices and collaboration expands monitoring, reduces costs, and fosters local stewardship, offering a scalable, sustainable solution to mitigate environmental impacts on submerged cultural treasures. 

References: 

[1] P. Michalis, C. Mazzoli, V. Karathanassi, D. I. Kaya, F. Martins; M. Cocco, A. Guy and A. Amditis, "THETIDA: Enhanced Resilience and Sustainable Preservation of Underwater and Coastal Cultural Heritage," IGARSS 2024 - 2024 IEEE International Geoscience and Remote Sensing Symposium, Athens, Greece, 2024, pp. 2208-2211, doi: 10.1109/IGARSS53475.2024.10642229. 

[2] L. Pavlopoulos, P. Michalis, M. Vlachos, A. Georgakopoulos, C. Tsiakos and A. Amditis, "Integrated Sensing Solutions for Monitoring Heritage Risks," IGARSS 2024 - 2024 IEEE International Geoscience and Remote Sensing Symposium, Athens, Greece, 2024, pp. 3352-3355, doi: 10.1109/IGARSS53475.2024.10641101. 

Acknowledgement: 

This research has been funded by European Union’s Horizon Europe research and innovation programme under THETIDA project (Grant Agreement No. 101095253).