If a diver has a 30-minute surface interval after diving to 18 m/60 ft for 33 minutes, how long can they dive to 17 m/58 ft?

To determine how long a diver can stay at a depth of 17 m (58 ft) after having already completed a dive to 18 m (60 ft), it is important to consider the dive tables or recreational dive planner specific to the conditions of the first dive and the surface interval.

After diving to 18 m for 33 minutes, the diver creates a certain level of inert gas saturation in their body. The 30-minute surface interval allows for some of this gas to be off-gassed, reducing the diver's nitrogen levels.

Consulting dive tables or resources, a dive to 18 m for 33 minutes typically requires a specific amount of time to desaturate before making subsequent dives. After the initial dive, and with a 30-minute surface interval, tables indicate that the diver is still within safe limits to perform another dive, albeit for a shorter duration than the previous one.

Diving to a slightly shallower depth of 17 m means that the diver's no-decompression limit for that depth is longer, influenced by both the depth and the surface interval. Hence, the diver should be able to spend a maximum of 32 minutes at that depth without entering decompression status, taking into account their previous dive and the