Technical diving, deep diving or any type of diving without direct access to the surface. It's not for the faint hearted and not something you 'just do'. Technique, planning, calculations, nothing is left undiscussed before doing a technical dive. Tec diving, cavern and cave diving, trimix diving, CCR diving, rebreather diving, sidemount diving. Expand your limits and do a tecrec or fundamental course all the way up to technical diving instructor.