In the period 1961–2024, the mean annual sea level along the Slovenian coast increased. The mean annual sea level at the Koper tide gauge station reached 233 cm in 2024 and was the second highest in the comparative period 1991–2020. The highest annual sea level of 322 cm represented the third highest sea level after 1991, while the lowest annual sea level of 142 cm was the second highest among the lowest recorded sea levels after 1991.

Phytoplankton biomass, expressed as chlorophyll a concentration, reflects nutrient loading in the marine environment. Chlorophyll a concentrations shows a trend towards improvement in the status of the Slovenian sea, as the ecological status has been assessed as high or good over the last period.

The quality of bathing water along the Slovenian coast is excellent, which ranks Slovenia at the top among the EU countries.

Nutrients, especially nitrogen and phosphorus compounds, are important for the growth of algae and higher plants, but in high concentrations can cause undesirable changes in aquatic organisms and seawater quality. Long-term measurements of selected nutrients in the Slovenian sea show that their concentrations have decreased significantly. Therefore, the ecological status of the Slovenian Sea is assessed as good to very good based on nutrients in recent years.