What we have found regarding how far one can swim in the ocean is that, in general, on average one can safely swim half of the total distance that they can swim (for an out and back swim). That is to say that if one can swim a total of 5 miles, then, they can swim 2.5 miles out into the ocean. (Thus, they will swim 2.5 miles back to shore; totaling their 5-mile max).
In a typical marathon, the winner will cross the line in a little over 2 hours. This means the pace they ran was around 5 minutes per mile (3 minutes per km). Ultramarathons tend to be a little slower, due to the excessive distances of those events. For a 50 mile ultramarathon, the first finishers will come in around the 5.5-hour mark, an average of 6:30/mile (4:00/km).
Triathlon is a sport that relies heavily on the cardiovascular system (hence why refer to these kinds of activities are often referred to as “cardio”). Any endurance sport that can be done for a sustained period of time while utilizing oxygen as the primary source of energy production is considered an aerobic sport, thus, Triathlon is categorized as an aerobic sport.
The choice is totally personal. The advantages are relatively small, but it’s probably worthwhile. At the top end, triathlons are all about tiny marginal gains. Any small little advantage or method can be the difference between winning and losing. If you don’t take it, you’ll be on the wrong side of that divide. If you’re already a pretty high-level triathlete then yes, you probably should shave your legs.
The inherent properties of water (buoyancy, viscosity, hydrostatic pressure, and temperature) add to the physical benefits of swimming and hydrotherapy- making either an excellent choice for the management of conditions such as arthritis, muscle/nervous system conditions, general fitness, or for rehab/recovery post-injury/surgery. Both activities are not only beneficial in general for the aforementioned areas/conditions, but are also specifically beneficial for soft tissue injuries such as strains, sprains, and tears- after proper healing and once cleared for such activities, of course.
The range of options here includes everything from going “commando” (i.e. nude/wear nothing, au natural) to wearing a garment specifically designed to be worn under them, and everything in between- including everyday underwear . Ultimately, it depends on one’s preference. However, the type/style of swim shorts will certainly persuade and/or dictate what one wears (or doesn’t wear) underneath them as well.