A bikini, somewhat like this, https://www.google.com/search?biw=1215&bih=608&tbm=isch&sa=1&ei=ARMHW_WWMIvKjgSApJXgAQ&q=bikini+for+kids&oq=bikini+for+kids&gs_l=img.3..0l5j0i30k1j0i5i30k1l4.5721.8205.0.8342.9.9.0.0.0.0.127.929.4j5.9.0....0...1c.1.64.img..0.9.926...35i39k1j0i67k1.0.vX5nYHwqdTM#imgrc=cEdSzcVUBY3jUM: Or a full one, like this? https://www.google.com/search?biw=1215&bih=608&tbm=isch&sa=1&ei=PxMHW7y4FIzcjwS1prDgDA&q=swimsuit+for+kid&oq=swimsuit+for+kid&gs_l=img.3..0l6.6709.10083.0.10636.14.12.0.2.2.0.119.1171.7j5.12.0....0...1c.1.64.img..0.14.1178...0i67k1.0.L-nn19xsoeU#imgrc=8_hpW3MZi7NjCM: