ALL ABOUT THE START.
With the exception of a few specific races, there are two ways you will start a traditional triathlon…either wading in deeper water or beachside which requires a running start. If you start beach side or even in ankle deep water, you will quickly discover you can only run so far in the water before it becomes counterproductive. Unfortunately, you may still be too shallow to start swimming! So what do you do? Many triathletes will "dolphin" for several yards until they are deep enough to begin swimming. "Dolphining" refers to a swimmer taking a shallow dive or leap forward, gliding for a few yards under water, then standing and leaping out again until the swimmer is deep enough to begin swimming.
GoggleProject suggest you will probably find the more competitive and/or experienced swimmers performing this technique. However, it is not necessary. There is nothing wrong with walking into deeper waters before swimming.
Plus, if you are among a large group at the start, most likely, you will not have the room to dolphin. This too will be a result of how competitive you want to be and your swimming background. NOTE: One note of caution…if you do dolphin…DO NOT DIVE DEEP! If you dive too deep you can seriously injure yourself.
Know the depth of the water where you are swimming and keep the dive portion of the entry shallow.
Finally, regarding Positioning at the start - if you have problems with the masses, then stay out of them! Place yourself to one side of the group or the other prior to the start.