Crawl stroke or freestyle can be an easy way to move through the water if you can control your breathing. Remember to blow your air out from your nose and mouth under water before turning or lifting your head for a breath with just your mouth. This will allow your body to stay at the surface and continue forward momentum. The longer your head is above water, it takes more energy to keep swimming. Take two or three strokes with your head under while exhaling before grabbing another quick breath and pressing your forehead back down underwater. Try to keep your arms long and go at an easy pace so you don't tire yourself out.