What do you notice about the design of a regulator second stage? At first glance a diver may notice the size, weight, or color. Perhaps you notice an interesting little knob on the second stage labeled "Dive/Pre-Dive," "On/Off," or "+/-". This switch or knob alters the airflow inside the regulator, making breathing either easier or more difficult. Turning the knob enables and disables something called the Venturi Effect, which regulator designers take advantage of to assist breathing. Click through the following pages to find out how it works, and when you should disable the Venturi Effect. Read more
More regulator articles:
• DIN vs Yoke Regulators
• What Is a Balanced Regulator?
• Definition and Basic Parts of a Regulator
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Sporting outrageous hues and patterns, marine angelfish make diving a colorful experience. The seventy-four known species of angelfish have an amazing variety of sizes, shapes, and colors. Divers will recognize the typical angelfish shape in such species as the Queen Angelfish and Gray Angelfish: flat, rounded bodies and long, trailing anal and dorsal (upper and lower) fins. Imagine turning an angelfish on its tail, with its fins hanging down, and the reason for the name becomes apparent. The shape of the fish turned this way resembles the silhouette of an angel. Here are twelve fantastic angelfish to look for on dives around the world. 
Diving on a shipwreck, I look up while inside a cabin and see a pool of air from my exhaled bubbles. The pool shimmers, mirror-like, and for a moment I see my own image gazing back at me. I make a face at my reflection and breathe out. The exhaled air hits a different part of the ceiling. Large bubbles burst into a thousand tiny particles upon impact, and then slither like quicksilver up to the larger pool. Magic! I am obsessed with scuba diving. How do I love diving? Let me count the ways: 
Why did I switch to the Mares Excel Plus Fins? Since the beginning of my career as a cave diver, I have used the quintessential cave diving fin: the SCUBAPRO Jet Fin. Jet fins are excellent for frog kicking and make back kicking easy. I have tiny feet (US woman's size 5) and my jet fins looked like miniature models of the jet fins that all my taller and bigger cave diving buddies were using. The blades were much shorter, and they were not as wide as my friends' larger fins. Because I am so small, the size of my fins was never a problem. I am small enough to have less drag than the average diver, and I could swim just as quickly as everyone else. However, when I started carrying multiple stage tanks on my dives, my tiny fins were no longer sufficient to propel me efficiently through the water.