[Yossarian]

It is both depending on training regiment. You can swim slower distance reps for aerobic development and sprint sets for anaerobic.

True. I generalized.

Now if you are a swimmer with poor stroke efficiency as most triathletes are, than it will be more of an aerobic workout.

Ahem. Most triathletes, at least the ones I hung out with, are maniacal about stroke efficiency - even more so than the swimmers I know. It is the same way on the bike - we are way more paranoid about aerodynamics than just straight bikers. We know that we have to maintain muscle energy and fuel for the long run - so we'd rather be efficient but maybe a bit slower, rather than flail around with better speed.

It's why we kick slower in our swim style, too. This may be why I had drilled into me that swimming is anaerobic - because for a good triathlete, that's the case.

Please check out Total Immersion Swimming.

Yes, that is a very popular system with many triathletes I know.

[PA Engineer]

Ahem. Most triathletes, at least the ones I hung out with, are maniacal about stroke efficiency - even more so than the swimmers I know.

I stand by what I said. The three triathletes I worked with last summer were excellent on the biking and running, but horrid in stroke efficiency.

It's why we kick slower in our swim style, too.

Ahem. Kicking is the weakest portion of the front crawl and is used more for body stabilization during high stroke efficiency. Unlike breaststroke and to some degree butterfly, kicking is a minor component of freestyle (front crawl in this case).

Yes, that is a very popular system with many triathletes I know.

After reviewing you knowledge of swimming you should check it out.