# Integrating Blockchains with the IoT: A Review of Architectures and Marine Use Cases
## 6 Conclusions  
This work explored the integration of blockchain technology with the IoT in marine environments, specifically within MIoT and IoUT systems. Key motivations for adopting blockchains in these settings include data security and configured decentralization. Specifically, this work revealed the need to place emphasis on the importance of lightweight nodes in BIoT systems, a trend reflected in the solutions examined, many of which avoid PoW due to its high energy demands. Instead, custom blockchain solutions frequently employ other consensus protocols (e.g., PoA\({}_{1}\), PoA\({}_{2}\), PoQ, modified PoW, modified PoS, etc.) in order to accommodate the specific limitations of marine environments. Ethereum remains a prominent platform, though the need for specialized solutions is evident given the unique challenges of the marine IoT. The primary challenges that were identified are related to energy constraints, protocol standardization, data handling, and system scalability. Future advancements in blockchain and IoT integration will need to address these issues by refining consensus mechanisms, optimizing performance, and enhancing interoperability to enable more efficient and adaptable solutions for marine ecosystems. Further research is also required, in order to explore the broader adoption of Ethereum's PoS model as the technology continues to evolve to meet the specific demands of these environments. Additionally, future research will need to assess whether custom solutions will continue to prevail over standardized platforms, or if a shift toward more universal frameworks can effectively support the unique requirements of marine IoT applications.  
Conceptualization: E.I.; methodology: A.P.D. and E.I.; literature research: A.P.D.; software (DIGI4 ECO use case): E.I. and S.P.; writing--original draft preparation: [PERSON]. (main author) and E.I.; review: [PERSON], G.G., S.P. and A.P.D.; writing--final review and editing: [PERSON]; supervision of article development: [PERSON]; funding supervision: [PERSON]. All authors have read and agreed to the published version of the manuscript.  
This work was partially funded by the European Union DIGI4 ECO project, grant agreement ID: 101112883.  
The authors declare no conflicts of interest.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} AI & Artificial Intelligence \\ AIS & Automatic Identification System \\ ALOHA & Additive Links On-line Hawaii Area \\ AMUSE & Adaptive Modulation in Underwater Acoustic Networks \\ API & Application User Interface \\ BAM & Blockchain-Based Privacy-Preserving Authentication and Malicious Node Detection Model \\ BCoT & Blockchain Composite IoT Architecture \\ BFT & Byzantine Fault Tolerance \\ BIoT & Blockchain-enabled IoT \\ dApps & Decentralized applications \\ DPoS & Delegated Proof of Stake \\ DRL & Deep Reinforcement Learning \\ DTN & Delay-Tolerant Networking \\ EBSI & European Blockchain Services Infrastructure \\ FC & Fusion center \\ GPS & Global Positioning System \\ GUI & Graphical User Interface \\ IoT & Internet of Things \\ IoUT & Internet of Underwater Things \\ \end{tabular}