The relationship between ports and energy markets is undergoing a transition in their functions as suppliers, consumers, and energy processors. Environmental factors increasingly force the maritime sector to reduce its carbon footprint and improve energy efficiency. Governing the maritime sector’s environmental performance requires leveling decarbonization through integration with energy supply chains and rethinking green strategies and environmental sustainability. This paper highlights that a port’s energy management system can be an example of supply–demand equalizing sustainable alternative energy sources. Such systems engage more profoundly within the energy value chain by assessing green and environmental indicators in port operations, strategies, and investments. This manuscript investigates the challenges in ports’ operations, strategies, and investments, considering their energy transition and decarbonization. Therefore, this research conducted a qualitative study on ports’ energy efficiency and greening using an in-depth interview method in three seaports in the Adriatic, Baltic, and Black Sea basins. The paper proposes a framework for analyzing green variables in the ports’ operations, strategies, and investments to improve their environmental performance. The framework examines a set of green variables, researching their cause-and-effect relationship, enabling testing and evaluation of the determined relationships, and identifying asynchrony in the balanced development of green investments and energy efficiency.

The economic prosperity of maritime regions depends on the development of nautical ports and related activities. Therefore, nautical ports and nautical tourism are essential for the creation of jobs and revenues and for the coastal and island communities' overall social and economic development. Moreover, high revenues generated by nautical tourism have a significant share in total revenues from tourism as the primary source of income in the Croatian economy. Therefore, this paper investigates the total revenues of nautical ports by proposing a model consisting of three steps: 1) classification of input variables into three categories: environmental, social, and economic according to the fundamental aspects of sustainable development; 2) application of the principal component analysis to each category to form new variables as representatives of the categories; 3) application of the multiple regression method for the analysis of total revenues. Statistical analysis and comparison of the results show that the proposed model well expresses the total revenues, r(2) = 0.92, with confirmed statistical significance. Thus, the analysis and the proposed model enable not only a more objective understanding of the observed system, but also the analysis of its sustainable development, and a decision-making process.

The tourism industry is among the fastest growing globally, with an oversized increase in travelers, businesses, and activities. Besides tourism’s considerable economic benefits, its adverse social and environmental impacts are rising, including the depletion of natural resources, pollution, loss of authentic local cultures, seasonal pressures, and more. Tourism, particularly the nautical sector, largely depends on natural and social capital, jeopardizing them through continuous growth and expansion. For instance, it vastly pressurizes the marine environment and communities during peak season, resulting in expanded pollution, water deficit, traffic congestion, and decreased quality of life. However, the nautical sector generates considerable jobs, revenues, and economic growth for coastal communities worldwide. Numerous coastal economies depend solely on tourism, with nautical ports playing a significant role in the sector. Many nautical ports focus on sustainable development and seek degrowth strategies. This chapter uses the value chain to investigate degrowth solutions in nautical tourism. It creates degrowth value chain framework for nautical ports that considers sustainable solutions across their primary and support activities. The proposed framework is based on secondary data related to the ports’ business practices, requirements of eco-certificates, sustainable development goals, and green innovations in the nautical sector.

Global development in recent decades has beencharacterized by increased resource consumption andgrowing environmental pressures, highlighting the need forsustainable economic and social progress. Tourism, despiteits significant contribution to economic growth, often putspressure on natural resources and ecosystems, underscoringthe need for sustainable development in territories withsubstantial rural characteristics, such as islands. Thispaper examines the role of green transformation as adriver of economic resilience and sustainable developmentof Croatian island economies. Research was conductedamong stakeholders in island destinations who are involvedin tourism planning, development and management, usinga structured questionnaire survey. The results from PartialLeast Squares Structural Equation Modeling (PLS-SEM)show that green transformation of tourism positivelyinfluences all four sustainability dimensions of destinationdevelopment, with the strongest effect on environmentalsustainability. These findings support decision-makers inshaping development strategies for island destinations.

Sanitary wastewater discharges from recreational vessels are a difficult-to-quantify source of pressure in coastal anchorages because discharge events are intermittent, mobile and strongly dependent on user behaviour. We developed an integrated screening framework that jointly interprets environmental state (faecal indicator bacteria; FIB), pressure proxies (instantaneous vessel abundance and size structure), and behavioural/infrastructure context (a survey of wastewater systems and disposal practices). Ninety-six seawater samples from three stations were analysed for Escherichia coli and intestinal enterococci during 32 morning/afternoon campaigns. All individual samples were below the Croatian single-sample thresholds for excellent sea-bathing quality (E. coli < 100 and intestinal enterococci < 60 CFU/100 mL), although intestinal enterococci and E. coli were detected in 32% and 15% of the samples, respectively. The microbiological signal was descriptively stronger in the morning even though vessel abundance was substantially higher in the afternoon (121 vs. 266 vessels), and the highest FIB concentrations occurred at the southern low-local-pressure reference station, which had the fewest observed vessels (44). These differences were not statistically significant. Survey data showed that 82% of the respondents used vessels equipped with black-water-holding tanks, while marina pump-out facilities were used infrequently and disposal during navigation was reported more often. The integration therefore lies in triangulating non-equivalent lines of evidence: microbiological signals, observed boating pressure, and user/infrastructure conditions. This approach is intended for first-line screening and targeted monitoring, not for direct source attribution.