So it reaches 1000 atm during ascent at ~7300 meters. But question asks for depth before reaching — so maximum depth where it's ≤1000. - Sourci

Understanding the Context

What Is 1000 Atm in Pressure Terms?

At sea level, atmospheric pressure is roughly 1 atmosphere (≈101.3 kPa, 14.7 psi). Pressure increases by about 1 atm every 10 meters under water or in dense air. Thus, 1000 atm corresponds to approximately:

• ~10,000 meters underwater or
  
• ~9,800–10,500 meters in dense atmospheric conditions

However, in real-world scenarios, 1000 atm ≈ ~1000 bar, which corresponds more accurately to around 9,850 meters of water pressure, since 1 bar ≈ 10 meters of water column.

Key Insights

Pressure Increase with Depth: A Key Reference

Water pressure rises by roughly 1 atm per 10 meters (or 10 bar per 100 meters) due to hydrostatic compression. For theoretical calculations:

• At 7300 meters, pressure ≈ 730 atm (about 739 bar)
  
• Pressure exceeds 1000 atm somewhere beyond ~9800 meters
  
• A pressure of 1000 atm (~1000 bar) occurs at approximately ~9,850 meters under pure hydrostatic conditions (assuming seawater density and no compressibility effects)

But during ascent, pressure decreases—so the maximum depth where pressure is at or below 1000 atm occurs before reaching 7300 meters, likely just a few hundred meters below 10,000 meters.

Final Thoughts

Maximum Depth with Pressure ≤1000 Atm

During ascent from extreme depth, air or water pressure drops. The critical point is:

> The maximum depth where pressure remains ≤1000 atm is approximately during ascent from depths deeper than ~9800 meters, but not beyond ~10,500 meters, where pressure first exceeds 1000 atm on descent.

So, for pressures ≤1000 atm, the upper limit during ascent is roughly around 9,800 meters—below 10,300 meters, meaning pressure stays safely below 1000 atm throughout the climb from such depths.

In summary:
The maximum depth before pressure exceeds 1000 atm during ascent is about 9,800 meters, well before reaching 7300 meters.