text: It depends what you consider difficult.. \n\nbutterfly yea.. you'll get tired pretty quick, those underwater streamlines after the turns kill and its hard to keep your stroke going\n\nbreastroke for me is the hardest, it might not be as tiring but man.. It takes for ever to get to the other side.. and holding your breath after the turn for those long pullouts, it gets to you\n\nback.. hard to stay in line, hard to time turns, hard to stay down underwater facing up with water wanting to come in your nose\n\nfree.. easy? try doing it for 1500m.. keeping your stroke going is the hard part of free, sure its probably the easiest but if you want to go fast, it takes a loooooot of time and practice\n\nIn my opinion, fly is the hardest, but to be good in a stroke is hard for all