logo mares horizon


The Mares Horizon is a Semi-Closed Rebreather designed with one clear purpose: simplicity! It is easy to setup, transport, dive and maintain because every component of the unit is accessible by the user.

The Mares Horizon maintains a minimum flow rate of 5 liters/minute via the orifice at all times. During a dive, the fraction of oxygen in the loop is constantly measured and when it drops below the set point, an electronically-controlled valve (the EAV) opens. This valve injects fresh nitrox into the breathing loop until it reaches the set point. The EAV can inject nitrox with maximum flow of 25l/min, so together with orfice, Mares HORIZON is able to provide 30l/min of nitrox flow into the breathing loop. This is more than enough to maintain safe breathing gas even with very high exertion.

SCR Side profile


  1. Height: 54 cm
  2. Width: 40 cm
  3. Depth: 22 cm
  4. Unit weight: 12 kg (without regulator set)
  5. Complete non-deco version weight: 13.4 kg
  6. Complete full deco version weight: 14.8 kg


  1. Two (2) scrubber canisters, each containing 1 kg of CO2 absorbent that can be refilled by user
  2. Two (2) integrated weight pockets, each containing a maximum of 2.5 kg of weight
  3. Fully adjustable harness system, from XS to XXL
  4. Safety gag strap on mouthpiece
  5. 2 oxygen sensors
  6. Constant oxygen fraction supplied to the diver, adjustable during diving
  7. Reverts automatically to full nitrox breathing in case of failure
  8. Remaining scrubber time calculated by the dive computer
  9. No tools required for preparation, use, cleaning


  1. Maximum recommended depth using one stage cylinder as gas supply, no decompression: 30 m
  2. Maximum allowed depth using two stage cylinders as gas supply: 40 m
  3. ppO2 during use: minimum 0.22 bar, maximum 1.60 bar
  4. Water temperature: minimum 4°C, maximum 34°C
  5. Allowed nitrox mix: minimum 30%, maximum 99%
  6. Approved scrubber material: Sofnolime 797
  7. Scrubber material endurance depending on temperature and metabolic oxygen consumption:
    calculated by the dive computer (i.e. at 15°C or higher, with medium/high oxygen consumption, duration is > 3 h)
    75 RMV at 40 m, CO2 production of 3 l/min for 5 min


  1. Three sets of redundant electronics, each with an individual battery system
  2. All battery systems can be charged from one single point
  3. 2.8” full color, high contrast dive computer screen
  4. User adaptable gradient factor decompression algorithm
  5. HUD with clear GOOD / FAIL indication
  6. Approved to 40m

aSCR + eSCR = hSCR

Mares Horizon is a Semi-Closed Rebreather that uses both active Semi-Closed technology and electronic Semi-Closed technology. This means that there is constant flow of Nitrox gas through the orfice and EAV (electronic addition valve) to help maintain the preset oxygen level.
unlimited time

Unlimited dive time

Can you imagine spending 5-8 times longer underwater compared to open circuit diving? Thanks to extremely low gas consumption in a semi-closed rebreather, your SAC rate is not a limiting factor anymore!


Simple logistics

New Mares Horizon is lightweight. It weighs only 14 kg when ready to dive as it doesn’t need any dedicated tanks. You can use a regular 5,7 l (S40) stage tank wherever you go. It is incredibly travel friendly.
fail safe

Fail safe

Mares Horizon has triple redundant electronics and redundant batteries. Moreover, it supplies continuous nitrox flow of 30l/min. in case of an electronics failure so no matter what happens, you are breathing a known gas and can finish the dive safely.

easy prepare

Easy to prepare

A truly revolutionary solution. The Horizon is probably the easiest rebreather to set up on the market. Just "plug and dive”. You do not need any additional tools.
unlimited time

For both recreational and technical divers

Its main purpose is to help:
- OC divers to cross the rebreather diving boundary
- RECREATIONAL divers to cross the technical diving boundary in super safe way

You can be trained for RECREATIONAL dives to 40m or TEC dives that include staged decompression. Mares Horizon offers an intelligent Dual Scrubber System as well as dual gas diving for accelerated decompression.