Flip Flops allow for sun on feet that get too little sun for most people
You want an equal amount of sun on all parts of body to maximize Vitamin D, Nitric Oxide, Sulfated Cholesterol and other beneficial chemicals without getting too much sun on any skin that leads to weathering overexposure.
Tank tops help get more sun and stay respectable.
But shirtless is better.
Shirtless is ok on the beach.
Honolulu and Myrtle Beach South Carolina gets water temp 82
much better than San Diego 72 or Anchorage 32.
Myrtle Beach is cheaper too.
Go to the beach daily to force you to stay in shape and prevent SHTF.
Use it or lose it.
Skin is a solar panel for your body.
Skin is the largest organ in the body.
Your mitochondria can run off sun in addition to food.