Complex sentence: The primary appeal is the opportunity to observe underwater life in a natural setting without the complicated equipment and training required for scuba diving and it appeals to all ages because of how little effort there is, and without the exhaled bubbles of scuba-diving equipment.
Split into simpler sentences: The primary appeal is the opportunity to observe underwater life in a natural setting without the complicated equipment and training required for scuba diving. It appeals to all ages because of how little effort there is, and without the exhaled bubbles of scuba-diving equipment.