Iso-Melkutin is a freshwater lake site in the Helsinki and Southern Coast region of Finland. The site features a varied topography including reef structures and kelp forests, with depths ranging from 2 to 27 metres. Divers typically experience 40-minute dives with visibility between 4 and 15 metres. The site is accessible via a shore entry and is suitable for intermediate divers. Conditions include mild currents and common thermoclines. Summer water temperatures range from 15.0 to 20.0 °C, while winter temperatures drop to between -2.0 and 4.0 °C. On-site facilities include parking, toilets, showers, changing rooms, a rinse station, air fills, equipment rental, a cafe, first aid, and gear storage.