Chios Strait Thermocline
Dive site
The narrow Chios Strait between Lesbos and Turkey creates a persistent cold-warm mixing zone where deeper cooler Aegean water upwells against warmer surface layers, generating a visible thermocline at 12 to 18 metres and concentrating planktonic biomass that attracts pelagic fish. Bluefin tuna and amberjack patrol the mixing layer in summer, while the nutrient injection supports dense meadows of Neptune grass. The thermocline itself appears as a shimmering refractive lens — a striking visual phenomenon divers cross repeatedly during the dive. Barracuda schools of 20 to 50 individuals are a reliable sight from June through October. The strait's currents vary with tide and season; experienced divers time entry for slack water.
Conditions
Depth
8 to 30 m
Open water and up
Current
Can be moderate
Can pick up on the edge
Visibility
15 to 22 m
Clearest in the calm season
Water
13 to 29°C
3mm wetsuit
Month by month
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Water (°C) | 14 | 13 | 14 | 15 | 18 | 22 | 25 | 26 | 24 | 21 | 17 | 14 |
| Vis (m) | 10 | 10 | 12 | 12 | 15 | 15 | 15 | 15 | 15 | 12 | 10 | 10 |
| Current | Strong | Strong | Moderate | Moderate | Moderate | Moderate | Moderate | Gentle | Moderate | Moderate | Strong | Strong |
Your chances of seeing each animal
Mediterranean barracuda
Photo: rovil · CC BY-NC
Rare
Now and then
Greater amberjack
Photo: Luis P. B. · CC BY-NC
Rare
Now and then
Bluefin tuna
Rare
Now and then
Atlantic bonito
Photo: Patrick E. Phoebus · CC BY-NC
Rare
Now and then
Field journal
No sightings recorded here yet.
Upload the first sightingDived here recently?
Your sighting helps us track reef health at this site in real time.
Submit a sightingPlanning to dive Chios Strait Thermocline?
Your underwater photos help scientists track reef health here in real time.
What to photograph: fish and marine life, coral (especially anything pale or unusual), anything unexpected.
How to capture it: shoot JPEG, keep location on, note your depth and the date.
Dived Chios Strait Thermocline recently?
Your photos help track reef health.
Up to 10 photos · JPEG or PNG · max 20 MB each
📷
Drag photos here, or tap to select
GPS in your photo will auto-detect the dive site
Gear