radically improved swimming technique

... because i currently do 500m in about 9.5 minutes.

it's really amazing, i improved my 500m time within one week from 10 1/2 to 9 1/2 minutes due to a swimming teachers hint. normally i breathed every second 'arm' during crawl. but the teacher told me it's much better to do it every three times because breathing with every second arm is too less streamlined. another hint was to put my head deeper in the water with the effect that my ass comes more to the surface. these two little hints improved my technique radically!!! :)