30's swimming in colour (with a little bit of late 20's thrown in for good measure)

1930's bathing suit at the Metropolitan Museum New York

via Velvet & Linen blog

1928 bathing suit via fuzzylizzie.com/swimsuits -
- on this website you will also find a great article on vintage swimwear

1929 bathing suit via fuzzylizzie.com/swimsuits - I love this one!!!

1932 wool swimsuit with adjustable ties via  fuzzylizzie.com/swimsuits

1936 swimsuit made of a lastex/wool mix for a better fit via  fuzzylizzie.com/swimsuits

Jantzen suit

1936 bathing suits at the Metropolitan Museum NY

 
red wool bathing suit by B. Altman & Co., 1932. via yeoldefashion tumblr

1933 bathing suit, via retroknittingcompany

via Sonne nach Wunsch flickr


And below, a pattern you can actually knit via A Stitch in Time vol 1.
This one comes with the perfect body too :)