SDI Open Water Scuba Diver Practice Exam

During a dive, the head is where the greatest amount of heat is lost due to several physiological and anatomical factors. The human head contains a significant concentration of blood vessels close to the surface, which facilitates heat exchange. When a diver enters cold water, these blood vessels can allow heat to escape more rapidly. Additionally, during immersion in water, the body's limbs become less insulated compared to the torso, which is typically covered in suit materials that provide some thermal protection. Although the hands and feet do contribute to heat loss, the head's exposure, coupled with its physiological characteristics, makes it the primary area for heat loss. Keeping the head covered while diving can help mitigate this effect and maintain overall body temperature during underwater excursions.