Lose overall BF. Can't target one place, unless you go under the knife.
Run, Bike, swim, lift weights, kickbox, rock climb, roller blade
The sad truth is that you cannot lose weight from just your stomach area - it doesn't work. You can reduce bloat, if that's your issue, but it sounds like you have fat or "flab" that is making you unhappy with how you appear (especially in a swimsuit, I'd imagine)? It also sounds like you are already in a healthy weight range, just concerned with that one area. If I'm correct, here is my advice from experience:
If you don't have stomach skin issues (stretch marks, loss of elasticity, etc.) then some overall weight loss/toning should give you a firmer stomach. You can do resistance/weight lifting workouts featuring core exercises (google it) for muscle tone and, more importantly, cardio (try intervals for faster results) to help burn the fat obscuring the muscles. Try to reduce calorie intake by 500-800 or so per day, eat a LOT of fiber through fruits/veggies (plentiful in summer) to keep feeling full, and eat healthy proteins like chicken, salmon, eggs, etc. The real key is meeting your nutritional requirements while creating a mid-level calorie deficit through working out. That should help you tone and feel beach-ready in a few weeks! Good luck!
Eat less, have good genetics , exercise
Fork put-downs and plate push-aways.
OMG thats funny.....and the best advice as well.