Being the heaviest living organism on the planet (that doesn't photosynthesise or isn't a ridiculously big fungi) , baring in mind that it lives in water, what's the fastest a Blue whale has been recorded swimming? being a huge lump of a mammal, it has probably never felt the need to out run anything or take on random spurts of speed to leap on krill, nor is it built to race...much at all...except krill..and maybe other blue whales for a mate. but theoretically how fast could a Blue Whale be if it let it's metaphorical hair down? Thomas Frost, Suffolk, UK