I often get the question, "How do I train in open water for distance?  What do I do?" I like to think of training in open water as similar to training in a pool. Of course it varies depending on the time of year and what you're training for, but the general outline goes something like this: warm-up, drill set, kick set, warm-up set, main set 1, easy swim, main set 2 (maybe), easy swim, timed sprints or X distance(s), cool down. Since I just wrote an article about this called "How Do I Train To Swim Faster In My Races" I won't get too detailed here. Instead I'll just give you another sample workout. Below is what I did the other day (July 27), which I would call a "moderate effort" workout in preparation for a 5k race in about a month.

There are many factors involved with swimming faster, both in competition and in practice (e.g. form, rest, hydration, nutrition, training schedule, warming up etc.) but the answer to the "train for race" question is simple: you have to swim faster in practice in order to go faster in competition. Seems pretty obvious to me, but I hear this a lot so I guess it isn't. But if you think about running, clearly a sprinter needs to sprint in practice to become faster, a distance runner needs to do longer intervals at higher levels of effort etc. in order to become faster. It's no different in swimming:  at some point in your training you actually have to "work", huff and puff, hurt a little (or a lot) and really push yourself in order to get faster. Puking is ok too, just like training for anything else (please, though, no dairy products before practice and please hurl your lunch in the gutter!).