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SS John Mahn Wreck

SS John Mahn Wreck

Central Belgium, Belgium

Depth
Depth Icon

40m

Visibility
Visibility Icon

6m - 18m

Entry
Boat Entry Icon

Boat

Experience Level

Advanced

SS John Mahn Wreck

Central Belgium, Belgium

SS John Mahn Wreck
Depth
Depth Icon

40m

Visibility
Visibility Icon

6m - 18m

Entry
Boat Entry Icon

Boat

Experience Level

Advanced


About SS John Mahn Wreck

The SS John Mahn was a German steamship that was constructed and built in 1927. She sank in February 1942 after being attacked by heavy air raids. She sank taking several crew members with her and today she is found in deep water that is only recommended for advanced divers. Since the area in which she is found is also a popular fishing area, you will need to watch out for nets. Marine life is various.

SS John Mahn Wreck Dive Info

Terrain & Features

Drift, Deep, Inland, Wreck

Entry Type

Boat

Max Depth

40m

Visibility Range

6m 18m

Experience Level

Advanced

Best Gas Mix

21% – 28%

O2

13% at 38m / 29%

O2
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Marine Life

  • Bass
  • Carps
  • Perch
  • Tench
Weather Conditions

Water Temperature
Dive Operators near SS John Mahn Wreck

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Location

Dive Site Hazards

  • Eddy Pull-Off Zones — Eddies behind structures can pull divers away from the main drift line.

  • Delayed Surface Pickup — Strong current can exceed surface tracking assumptions, delaying boat pickup.

  • Vertical Current Shear — Currents may vary by depth, causing vertical separation even when divers stay together.

  • Gradual Narcosis Onset — Narcosis may develop slowly, making self-assessment unreliable.

  • Task Fixation at Depth — Cognitive narrowing at depth can reduce awareness of time and ascent rate.

  • Increased Gas Density Breathing Load — Higher gas density at depth increases work of breathing.

  • Thermocline Buoyancy Shift — Sharp thermoclines can cause sudden buoyancy changes.

  • Instant Visibility Collapse — Sediment disturbance can eliminate visibility immediately.

  • Late Detection of Structures — Submerged structures may only appear at very close range.

  • Deceptive Entry Openings — Openings may become restrictive inside due to angle, collapse, or corrosion.

  • Surge-Induced Internal Silt Shift — Internal surge can move silt and debris without direct contact.

  • Partial Overhead Environment — Many wrecks limit direct ascent even without full penetration.

  • Fine Rust Particle Silt-Out — Disturbed rust particles can rapidly reduce visibility.

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