Galectin-3 (Gal-3) is β-galactoside lectin expressed in wide range of cells which mediates different physiological (apoptosis, proliferation and differentiation, signalling) and pathophysiological (inflammation, fibrosis, cancerogenesis) events. Its role as biomarker in cardiovascular diseases, organ fibrosis and different tumors has been intensively studied. It is being used as a biomarker for risk assessment of heart failure and as a tool in management of thyroid nodules. Some studies showed that Gal-3 increases after physical acitivity, so the aim of this study was to investigate potential impact of recreational SCUBA diving on Gal-3 plasma levels. Ten healthy men, aged 30-52 years, performed a 30-minute SCUBA dive at 30 m depth which was their first dive after a winter non-dive period. Venous blood samples taken on anticoagulant K2EDTA were obtained from the subjects before and immediately after the dive, 3 h and 6 h after diving. In plasma samples, taken in vacuum tubes, Gal-3, biomarkers of cardiac injuries (NT-proBNP, hsTnI), skeletal muscle damage (myoglobin) and systemic inflammation (hsCRP) were measured. The obtained data were statistically analyzed in MedCalc using Friedman ANOVA test. A significant increase (p < 0.05) in plasma concentration was found with respect to baseline values immediately after diving for every parameter except for hsCRP. It was also found that Gal-3 levels were higher 3 h after diving with respect to baseline levels in clinically important settings, as for NT-proBNP and hsTnI which also showed clinically important higher values 6 h post-dive. This research showed for the first time that SCUBA diving causes Gal-3 release into the blood. The results suggest that Gal-3 might originate from heart since there is an increase in NT-proBNP and hsTnI (which are specific for cardiomyocytes); but from skeletal muscle since myoglobin concentration raise as well.