1At a glance
- Category
- Equipment configuration
- Cylinder placement
- Lateral torso (under armpits)
- Typical tank count
- 1 or 2 cylinders (plus stages)
- Primary advantage
- Streamlining, redundancy, back relief
- Certification agencies
- PADI, SSI, TDI, RAID, IANTD
- Key applications
- Cave, wreck, extended recreational
- Gas balance protocol
- Switch regulators every 20–30 bar
2How sidemount configuration operates
Sidemount hardware centers around a minimal harness integrated with a spine-mounted buoyancy compensator (wing). Cylinders rest parallel to the diver's spine beneath the armpits. The upper neck of each cylinder attaches to a chest-level shoulder bungee, keeping the valve tucked close to the armpit, while the lower cylinder body clips to a sliding D-ring on the waist belt.
As gas is consumed during a dive, aluminum cylinders become positively buoyant at the tail end. To maintain flat horizontal trim, sidemount divers move the lower clipping points forward along sliding waist D-rings. This adjustable geometry keeps the cylinders aligned with the body throughout the entire dive without creating drag or pulling the diver's legs downward.
Gas management requires disciplined execution. Because each cylinder operates as an entirely independent system with its own submersible pressure gauge (SPG) and second-stage regulator, the diver breathes from one tank until its pressure drops by 20 to 30 bar, then switches to the alternate regulator. This routine guarantees equal balance and preserves half of the total gas volume in reserve if one system encounters a failure.
3Sidemount compared to backmount and twinsets
| Configuration | Cylinder placement | Gas redundancy | Ease of gear entry | Best suited for |
|---|---|---|---|---|
| Single backmount | Single tank mounted on back | None (single valve/first stage) | Moderate (heavy on back on land) | Standard recreational profiles |
| Twinset / Doubles | Two manifolded tanks on back | High (via isolation manifold) | Demanding (heavy deck walking) | Deep technical open-water dives |
| Sidemount | Two independent tanks at flanks | Complete (two standalone systems) | High (can don/doff in water) | Caves, wrecks, back-relief recreational |
| Rebreather (CCR) | Backmount unit + small diluent/O2 tanks | High (with off-board bailout) | Complex (requires pre-dive assembly) | Extreme depth and long durations |
4What sidemount means for liveaboard diving
Adopting sidemount on a liveaboard trip dramatically alters deck and tender logistics. Rather than standing up with 30 kg of metal on your back, you can enter the water wearing only your harness and mask, having deckhands pass the cylinders to you in the water. Upon returning, you unclip the tanks at the stern or tender ladder and hand them up individually, reducing physical strain on your spine and knees.
In the water, sidemount unlocks exceptional stability and maneuverability around marine topography. The low-profile silhouette allows you to glide effortlessly through swim-throughs, overhangs, and tight wreck corridors without scraping overhead coral or bulkheads. Furthermore, having cylinder valves directly in front of your chest makes valve operation and leak troubleshooting simple and immediate.
However, diving sidemount on safari vessels requires advance planning. You need to ensure the vessel offers proper cylinder options, such as left- and right-handed modular valves or dual valve ports. Consulting with Blue Rides before booking helps confirm whether a specific boat's crew is trained in handling sidemount stages and managing tender drops for sidemount divers.
5Sidemount procedures across dive regions
| Region / Environment | Logistical considerations | Recommended setup |
|---|---|---|
| Mexico Cenotes | Tight limestone passages and haloclines | Dual aluminum AL80s, minimalist harness, short hoses |
| Red Sea Wrecks | Steel deck entries, current, deep wreck penetrations | Steel or AL80 cylinders with left/right valve sets |
| Komodo & Raja Ampat | Strong currents, zodiac/skiff water entries | In-water clip-on procedures, compact SPGs, high-visibility SMBs |
| Maldives Channels | Negative water entries, hanging in currents | Pre-clipped tanks for fast negative entries, short bungees |
6Common misconceptions
Myth: Sidemount is strictly for technical cave divers. Fact: While developed in overhead cave systems, sidemount is now widely used by recreational divers who appreciate improved trim, lower back comfort, and extended bottom times within normal recreational limits.
Myth: Any liveaboard can accommodate sidemount without prior notice. Fact: Sidemount requires specific valve setups (left- and right-handed orientation) and specialized tank filling arrangements. Boats must be notified ahead of time to prepare compatible cylinders.
Myth: Sidemount gives you double the dive time without tracking gas. Fact: Having two cylinders increases overall gas capacity, but active gas management is mandatory. Divers must switch regulators every 20–30 bar to maintain balanced trim and redundant reserves.
Myth: Donning sidemount gear takes much longer than standard backmount. Fact: Once the harness is fitted and muscle memory is established, clipping two tanks in the water takes less than a minute and eliminates heavy gear lifting on deck.
FAQ
Do I need a special certification to dive sidemount on a liveaboard?
Most liveaboard operators require an official sidemount certification card from a recognised training agency like PADI, SSI, TDI, or RAID. Showing your certification ensures the crew approves your configuration and provides compatible cylinders.
Can I rent sidemount cylinders on liveaboards?
Many liveaboards stock sidemount tanks equipped with left- and right-handed valves, but availability varies. You should always request sidemount cylinders during booking so the vessel can prepare the correct valve sets.
Is sidemount diving safer than single-tank backmount?
Yes, because sidemount uses two completely independent cylinder and regulator systems. If a valve or first stage malfunctions, you can shut down the affected side while continuing to breathe from the other.
How do you enter the water from a dive boat when sidemount diving?
Divers can complete a giant stride with tanks attached or put their gear on in the water. In-water donning involves jumping in wearing just the harness and wing, then clipping on tanks handed down by the crew.
Why do sidemount divers switch regulators during a dive?
Divers switch regulators every 20 to 30 bar to keep cylinder pressures balanced. Equal weight distribution maintains flat trim and prevents one side of the body from riding lower in the water.
Can I dive sidemount using standard single-valve aluminum tanks?
Standard AL80 tanks can be used by adding modular valve inserts or valve extensions. However, dedicated left- and right-facing valves are ideal because they position the pressure gauges and valve knobs inward toward the chest.
