SDI Open Water Scuba Diver Practice Exam 2025 – Complete Test Prep

The type of alternate air source that does not necessarily require the donor to give up his primary second stage is the conventional alternate-air-source second stage. This type of system typically involves a dedicated second-stage regulator (often referred to as an "octopus") that is connected to the tank but does not rely on the donor’s primary second stage for air supply during an emergency.

In scenarios where a diver experiences an out-of-air situation, the donor can share air without losing their own source of breathable air, allowing both divers to remain equipped with their primary second stages. This setup provides a safety net, ensuring that the donor can maintain their breathing supply while assisting the diver in distress.

Other options involve scenarios where the donor may need to give up their primary second stage or rely on different systems for air sharing. For example, integrated systems often combine buoyancy and air-sharing features but may still require adjustments that could compromise the donor's primary air supply. Similarly, an emergency buoyancy control device might not provide adequate air-sharing solutions, making the conventional alternate-air-source second stage the most reliable option in this context.