This all really depends on A. Vo2 at each discipline and B.HR Levels. For example I happen to burn to 15.2 kcal per hour/min at 187 bmp on the bike but 14.7 on the run. Small difference but it's there.
In my training swimming at my hardest effort for an hour doesn't equal the caloric expenditure of cycling or running at a moderate HR. On estimate I burn 300-420 kcal per hour swimming, 475-750 kcal per hour cycling, 500-650 running.

I have the same hunger probably after swimming....my appetite is insatiable.

running burns more than just about anything. don't try to thwart off your appetite, its there for a reason. its your body saying "Give me stuff to replce glycogen and repair muscles!" "Fuel me!" etc. when you are hungry, eat. eat the right stuff and you'll be good. also, if you are worried about consuming too many calories, try simple volumetrics w/ your food. find highly fiberous and high protein foods when you aren't training because they fill you up quicker and longer than carbs and fats. eat a large salad w/ meals, or add zucchini in lasagna. heck, get spaghetti squash and make pasta. very lean and very filling, a small bowl of spaghetti squash pasta w/ homemade tomato sauce will keep me full for a few hrs.

granted you want a good majority of the cal you eat 2 hrs pre/post workout to be carbs, so don't be shy on that, get as much as you can in there.

That my friend is called good genetics.

I wrote this sometime ago but I think you might find it useful. Obviously it's not going to be precise because we are all different but at least it gives you a general idea.

http://www.felog.net/utilities/cal_burn.asp

Swimming burns the least calories and generates the most hunger - so annoying. There are all sorts of theories as to why swimming causes hunger but none of them make a lot of sense to me. The heat one makes the least since since a hot cup of coffee and a hot shower in no way assuage my raging post swim hunger.

You just have to learn to let the hunger pass once you've eaten. The other solution is to run or ride after swimming. It fixes your appetite right up and justifies consuming more food!

Agreed - 3 hours of swimming on the part of a competitive swimmer is a little different than a 1 hour masters work out.

Don't forget to drink a lot after swimming too. I never feel thirsty after swimming due to not being able to tell that I may be sweating, but yeah, I am sweating. I'm just in a ton of water, so don't notice it, like with biking or running. I have found myself a little dehydrated before after some long swims...

I also do get hungry after swimming...don't know why either.