"I like swimming."
Translation:Ich schwimme gern.
From tips and notes: "What's the difference between gern and gerne? They're just variations of the same word. There's no difference in terms of meaning or style. You can use whichever you like best."
So if I'm not mistaken, "gern" more directly translates to "gladly" so instead of saying "I like swimming" we're saying "I swim gladly"?
"mögen" is no modal verb in the meaning of "to like". So you cannot connect it to another verb without forming a different clause for the second verb. "Ich mag es, zu schwimmen". would work. "Ich schwimme gern." is far more idiomatic though.
You could say 'Ich mag Schwimmen' (as a noun- 'schwimme' is outright wrong), but Duo's sentence sounds better.
You used the wrong word. Ich mag es zu schwimmen.
Is that a valid translation? I like it to swim?