Yüzmek*

To swim is easy> Yüzmek kolaydır.
Swimming is easy> Yüzme kolaydır. şeklinde düşünmüştüm. İlk cümle mastar, ikincisi isim değil mi?

İkincisi isim değil isim fiil -fiilimsi-. İsim fiilin diğer adlarından birisi de mastar.

İsim fiil olacağı için -me, -mek, -iş eklerinden birisi gelmesi gerekiyor da hani -mek daha fazla kullanılıyor diye yazmıştım. Zaten üzerine * koyarak yorum yaptım. Karar senin gene de.

May I add a comment here (or more a question indeed), to see if I understand my grammar book right:.
If the speaker has someone in mind who actually performs the swimming, he'd rather use 'yüzmek'. '(Benim icin) yüzmek kolay'.
If he just means the action of swimming in general, no matter who does it, then he'd use the short infinitive. The statement is more abstract.
I think English doesn't make this distinction (swimming - to swim), but it seems that the sentence refers to the act of swimming as such, thus - according to my grammar book - 'yüzme' could be more appropriate.

Does this make any sense to you?

Thanks brauchinet:)

Can you name your grammar book, brauchinet? It looks like it's a good one. I hope it's not "German to Turkish"

Anyway, we're all right. We have to add -me, -mek, -iş to make a verb verbal noun. So both yüzme and yüzmek are correct (also "yüzüş"). But for me, yüzmek sounds better.

Yüzmek kolaydır. - I think this is the best one.
Yüzme kolaydır. - 95%
Yüzüş kolaydır. - Correct but weird. Probably one one says it.

Thanks for all your comments.
Tatoeba as a Turkish grammar book.

@İlker: Alas, as you say, it's a German "Türkische Grammatik" and Turkish grammar is looked upon from a German point of view.
Thank you all for your comments!