Which of the following is least controllable by a dive team once they are committed to a dive?

The least controllable factor for a dive team once they are committed to a dive is environmental changes. Environmental conditions, such as water currents, visibility, temperature, and weather, can shift unexpectedly and are inherently variable. Once the dive has begun, divers have limited ability to alter these conditions.

While proper pre-dive planning is crucial to foresee potential environmental issues, once underwater, divers must adapt to what they encounter. Equipment malfunctions can often be anticipated and mitigated through thorough checks and maintenance before the dive. The diver's skill level is fundamentally a characteristic of the individual diver, and while it cannot be changed during a dive, it can be enhanced through training beforehand. Therefore, among the options, environmental changes stand out as the one factor that remains largely outside the team's control during the dive itself.