I swam for over 16 years competitively, and I am telling you from personal experience that its not good for getting cut. Trust me, I tried!! Maintaining an optimal HR for fat burning while swimming is not easy. Most of you would swim a 50 and be out of breath with a HR of 180. If you want to burn fat staying consistent for a long period of time is the goal. Stopping at the wall is not consistent. Most of you aren't in the kind of shape do swim a few thousands meters continuously without stopping. The human body wasn't made to swim, it was made to walk and run. You are better off on a treadmill or stairmill where you can monitor you HR.
If you want to get in shape from a fitness perspective swimming is great. But I warn you, swimming is not the kind of activity you want to do if plan on keeping your muscle.
Bash me all you want, but I am talking from personal experience.