Source : Webster's Revised Unabridged Dictionary (1913)

Swimmingly \Swim"ming*ly\, adv.
   In an easy, gliding manner, as if swimming; smoothly;
   successfully; prosperously.

Source : WordNet®

swimmingly
     adv : with great ease and success; "in spite of some mishaps,
           everything went swimmingly" [syn: {smoothly}]