Are you just learning to compete as a swimmer for a triathlon? Most people have grown up being able to swim so that much is not a problem, but learning to swim to race is another issue.
You need to learn how to do triathlon swim workouts and spend time in the water getting comfortable with it.
Consider this, you do not have to finish first in the swim section of a triathlon to win the race or place high in your age group.
Most races are won or lost on the bike or run so do not think you need to be an outstanding swimmer.
The least you should be doing when training for the triathlon swim is to become efficient at swimming so you are not worn out when exiting the water.
Learn how to properly swim so you are not exerting too much energy to get to the finish and you can have a faster start on your bike section.
If you want to go beyond just finishing the swim to swimming faster, you must crank up your training a couple notches.
You can not just swim up and down the pool counting laps, now you must start improving endurance, do drills and do intervals.
Working some fast intervals into your workouts will push you past your comfort zone and you will get faster.
You will also see an improvement in your endurance level from this.
Try using one of your workouts each week as a distance day.
Swim as many laps as you can non stop so you go further than what's normal for you.
This will help you get used to being in the water for longer periods and increase your endurance.