The Mariana Trench is the deepest part of the ocean at 36,201 feet deep. Conditions in the trench include very little light, heat, and extremely high pressure the deeper one goes. Special equipment like a wet suit, scuba gear, and tanks are needed to ensure safety at such depths. The human body can only tolerate 3-4 atmospheres of pressure, equivalent to around 33 feet, and temperatures are very cold below 16,000 feet where pressure increases dramatically. Reaching the depths of the trench would significantly impact body systems through risks like oxygen toxicity, nitrogen narcosis, dehydration, and the challenges of breathing and maintaining buoyancy and body temperature.