SSI Extended Range explained: Foundations, XR Nitrox, Trimix and beyond

Minimum ages: 16 for Foundations; 18 for the other programmes in this table. This is a summary: your instructor checks the full current standards, medical requirements and equipment before enrolment.

XR Foundations is a useful skills workshop, rather than a compulsory first step for every XR course. Its pool/confined-water sessions have a maximum depth of 12 m. You work on trim, buoyancy, propulsion and team procedures in technical equipment before any decompression diving. Before the next step you also need Deep Diving and Enriched Air Nitrox 40: see our articles on the Deep Diver course and the nitrox course.

Extended Range Nitrox Diving, Extended Range and Technical Extended Range use a twinset or an Extended Range sidemount system; a sidemount prerequisite applies when you use that configuration. Foundations allows several equipment configurations, including a single cylinder and appropriately qualified rebreather configurations. Hypoxic Trimix specifies a twinset with at least three stage cylinders. Our article sidemount vs backmount compares the two open-circuit options.

All three lead from limited decompression to full trimix diving, with different course names and steps. If you already hold a card from one agency, the best next step is usually to continue with that agency. Our guide to the technical diving path from Tec 40 to trimix explains the steps, and the technical diving hub lists every tec course we run.

Warm water, good visibility and deep walls and wrecks close to shore make the Red Sea a popular place to train. We also run technical diving day trips on the same boat as our daily diving. Narcosis, gas planning and decompression all become central at these depths, so take each step at its own pace.