(adsbygoogle = window.adsbygoogle || []).push({}); Title explains it all really :p, I'll include a poll so you can vote.

Clearly you guys haven't tried rowing, that's way more tiring than any of these. Skipping and rowing are my preferred favourites for cardio, but cycling is pretty good too seeing as it doesn't get boring that fast making you want to go for longer and work harder.

Yeah this is so true. I kinda forgot over the last couple years how tiring it is, kinda assuming that I could swim forever but after a few laps I'm knackered!

This is after like an hour session running and doing weights though so I guess it's not a fair comparison.

Its running, u can be sure

swimming more relaxing for me

Just like to point out that from my experience cycling is a stable cardio workout.
Based on the almost 3 weeks I have been doing it.

Swimming is amazing for the lungs, and is one of the best methods for cardio.

Swimming for sure. As long as you got on full utilities, boots, helmet, flack jacket, h-harness, cartridge belt, two magazine pouches, two full canteens with covers, rifle, and a 40lb pack. Otherwise you aren't doing it right.

Swimming is a good way, however so is running/cycling. So, up to you really.