What is the treatment for a diver surfacing without symptoms post-decompression?

When a diver surfaces without symptoms after a decompression dive, the appropriate treatment often includes administering 100% oxygen, especially if there is any suspicion of decompression sickness or excess nitrogen in the tissues. Providing 100% oxygen at the surface helps to enhance the elimination of nitrogen from the body and assists in preventing the onset of symptoms that may arise later.

This treatment also serves as a precautionary measure because decompression sickness can sometimes present symptoms after a delay. By using pure oxygen, the diver's tissues are more efficiently cleared of any residual nitrogen, which reduces the risk of potential complications.

The other options, while potentially relevant in different contexts or severity of symptoms, do not provide the proactive management that administering 100% oxygen offers. Simply observing without treatment might neglect the risk of developing symptoms later on, immediate chamber treatment may be unnecessary without signs of distress, and resuming normal activity does not account for the possible residual effects of decompression stress. Thus, administering 100% oxygen is the most effective and precautionary method in this scenario.