At the onset of menses the girl usually has reached 95% of her terminal height, most often reaching full adult size and stature within 1-2 years. There is a phase of rapid fat deposition in this 13-15 year old period, sometimes with a significant decrease in power and aerobic capacity. Performance measures peak at age 13 and then level off and decline. For some, this becomes a problem in the management of heavy scuba gear. Minimum size for comfort with conventional scuba gear is 45 kg (105-108 lb.) and 150 cm ( 60 inches). There is ossification of long bones in this period and concerns directed to the possibility of nitrogen bubble localization in the growth plates. This ossification (closure of growth plates) takes place one to three years sooner in girls than in boys, varying with the bone involved.
Young divers have several metabolic disadvantages. They become hypovolemic (low blood volume) much more rapidly than adults, generate more metabolic heat and burn more energy from a larger surface area to body mass ratio. Girls get colder more quickly than older women under similar environmental conditions, there being a 20 fold increase of conductivity into water. Greater thermal protection is needed for the young diver and the importance of a properly fitted wet suit is stressed.