Princess Islands in the Marmara Sea features a reef that transitions into a wall, with depths ranging from 25 to 80 metres. This site is suited for advanced divers capable of managing moderate currents and potential strong surges. Visibility is typically between 5 and 10 metres. A distinct thermocline exists at approximately 10 metres, where warmer surface water meets colder layers below. Water temperatures fluctuate significantly throughout the year, ranging from 1C to 18C, requiring appropriate thermal protection. Entry is possible from both shore and boat. On-site facilities include parking, toilets, showers, changing rooms, air fills, equipment rental, and boat charter services.

Prince Islands in the Marmara Sea offers boat-based diving at depths ranging from 5 to 30 metres. Divers should be prepared for strong currents and variable visibility between 10 and 20 metres. A distinct thermocline is often encountered around 10 metres, where warmer surface layers meet colder water below. Visibility typically improves at depths of 20 metres. Due to the strong currents and depth, this site is suited for intermediate divers. Boat traffic is a notable hazard in the area, requiring careful surface management. Water temperatures fluctuate throughout the year, ranging from 10C in the winter months to 19C in October.

Pigeon Cave in the Princes' Islands is a shallow, sheltered cave dive located in the Marmara Sea. With a consistent depth of 3 metres and no current, it serves as a suitable location for beginner divers gaining experience in overhead environments. Visibility typically ranges from 5 to 10 metres. Access is by boat, which allows for direct arrival at the cave entrance. The water temperature varies significantly throughout the year, ranging from 10C to 25C. Divers should exercise caution regarding buoyancy and wear gloves, as the cave features sharp rock edges on the walls and floor. Be mindful of surge and swell conditions during boat entry and exit.

Neandros Kufos reef is a deep-water site located in the Marmara Sea, requiring advanced certification and precise buoyancy control. The reef structure sits at depths between 25 and 35 metres, with an average depth of 25 metres. Divers must navigate moderate currents and visibility ranging from 5 to 10 metres. Due to water temperatures fluctuating between 10 and 19 degrees Celsius, full exposure protection is essential. Access to this site is by boat only, located over 2,400 metres from the shore. Divers should exercise caution regarding cold water and the presence of stonefish, avoiding contact with the seabed or reef structure at all times.

Neandros-Tektas is a reef site in the Princes' Islands, Turkey, offering a challenging dive for advanced divers. The reef sits at depths between 18 and 32 metres, with an average depth of 25 metres. Divers must access the site by boat. Conditions include moderate currents and visibility ranging from 10 to 30 metres. A sharp halocline exists between 20 and 30 metres, separating surface waters from saltier bottom layers. Water temperatures fluctuate between 10C and 19C throughout the year. Hazards include boat traffic and potential entanglement with submerged debris. Divers should use a surface marker buoy and maintain buoyancy control due to variable visibility.

The Karakaya Wreck is a marine dive site located off Heybeliada in the Princes' Islands. Resting at depths between 20 and 30 metres, the wreck provides a technical challenge for intermediate divers interested in penetration and navigation. Visibility at the site is variable, ranging from 3 to 20 metres, while currents remain mild. Water temperatures fluctuate between 10 and 19 degrees Celsius throughout the year, necessitating appropriate thermal protection. Access is strictly by boat. Divers should be aware of hazards including boat traffic and potential entanglement within the wreck structure. The site supports a variety of regional marine life and invertebrates typical of the Marmara Sea habitat.

Büyükada Kurşun Burnu is a reef and drift dive site located in the Princes' Islands, Turkey. This site is suited for advanced divers due to strong currents and depths ranging from 8 to 30 metres, with an average depth of 25 metres. Access is strictly by boat, and divers must remain vigilant regarding boat traffic in the area. The underwater environment supports a variety of regional marine life and invertebrates typical of the Marmara Sea habitat. Dives typically last 45 minutes, with water temperatures fluctuating between 10C and 19C throughout the year. The site is noted for its challenging conditions and suitability for deep diving.

Ay Yani offers a combination of reef and wreck diving located in the Marmara Sea. The site sits at depths between 39 and 45 metres, requiring advanced buoyancy control and careful management of bottom time. Divers access the site by boat, encountering mild currents and visibility ranging from 5 to 10 metres. Water temperatures fluctuate between 10 and 19 degrees Celsius throughout the year, with a thermocline present. Due to the depth and low visibility, this site is suited for intermediate divers. Divers should exercise caution regarding the depth and potential for sharks in the area.