Halcyon

Halcyon Symbios Handset

A modular technical handset with a sunlight-readable transflective display and CCR support.

Open BLE sync (libdivecomputer)

Syncs wirelessly with third-party apps (Subsurface, Currents, etc.), not just the manufacturer app.

Halcyon Symbios Handset
4.6Comparison Score
$900
Released2025
Max depth rating120m
AlgorithmZHL-16C with adjustable gradient factors
Air integrationwireless
Wirelessbluetooth
DisplayFull-color transflective display, five brightness levels
Batteryrechargeable
Digital compassYes
Gas typesair, nitrox, trimix
Gas switches5
CCR capableYes

"Gas switches" is how many different mixes this computer can be programmed to switch between mid-dive, mostly relevant for technical/staged-decompression diving. It doesn't tell you which gas types (air, nitrox, trimix) are supported. See Gas types and the product description above for that.

Pros
  • Transflective display stays readable in bright sun without a constantly-on backlight, saving battery
  • Up to 30 hours of runtime per charge
  • Displays CCR sensor data, buddy information, DPV and light status when paired with other Symbios devices
Cons
  • Price varies by finish/tier ($900-$1,195 depending on color and configuration)
  • Requires a Halcyon Tank POD for tank pressure display
  • Ecosystem-dependent, full feature set needs other Symbios-paired hardware
Diver community sentiment
Mostly positive

Across several Scubaboard threads, divers who have used the Symbios Handset consistently praise its design and readability, calling it sleek, easy to read even for nearsighted users, and paired with an unobtrusive, well-integrated HUD. Setpoint changes via haptic-feedback button presses were described as intuitive. The built-in trim inclinometer drew mixed opinions, some see it as a useful training aid, others worry it could become a crutch. One diver who ran the handset for about six months said it "works great" but flagged battery life and charging as the main gripe. Some GUE-affiliated divers were skeptical of how the broader Symbios/rebreather system is marketed as an easy CCR entry point.

Scubaboard: Symbios rebreather review, handset praiseScubaboard: early handset impressionsScubaboard: 6-month owner report on battery/charging

Summarized from public forum discussion (Scubaboard, Reddit, and similar), not a survey we ran ourselves. See the linked threads for the original conversations.

The Symbios Handset is the wrist-style computer in Halcyon’s modular Symbios system, built for technical and CCR divers who want a sunlight-readable display that can also surface tank pressure, buddy status, and CCR sensor data when paired with the rest of the ecosystem.