- + Very low internal volume (~60ml), minimal equalization effort at depth
- + Close-fitting single lens profile reduces drag
- + Excellent lens clarity
- + Durable build quality, strap and buckle are above average
- − Narrower fit, doesn't seal on wider or rounder face profiles
- − Single lens limits peripheral vision vs twin-lens designs
- − Requires careful strap adjustment to find the right tension
Overview
The Omer Alien is the usual step up from the Cressi Nano. The Nano works well at recreational depths, but for divers training consistently at 20-25m, its extra internal volume adds up over a full session of dives.
The Volume Advantage
Internal volume of approximately 60ml against the Nano's ~110ml. In practice: less air needed to equalize the mask at every depth, meaning more oxygen stays in your blood for the dive itself. This compounds over a training session with 20-30 dives. The carbon-framed Salvimar Drop sits in the same volume range if you want a lighter frame.
At shallow depths, the difference is irrelevant. At 20m+ with repetitive dives, it contributes to a measurably fresher feeling through the session's later dives.
The Fit Caveat
The Alien's single teardrop lens sits close to the face, which creates its volume advantage. The close fit also means the skirt has a narrow sealing footprint. Average and narrow face profiles seal reliably. Wider faces (broader cheekbones, rounder profiles) often find gaps at the sides of the skirt, and for them the broader skirt on the Mares Sealhouette is the usual alternative.
This is not a defect. It's a geometry trade-off. If you're buying online without trying it first, do the suction test against your face (no strap) before your first dive. If it doesn't hold, return it.
Build Quality
The buckle and strap system is noticeably better than the Cressi Nano. The buckle teeth are stiffer and hold the strap adjustment securely. The silicone skirt has a softer durometer than some competitors, which contributes to the seal quality.