How do you make a smooth canter depart?

A smooth canter departure is the product of preparation, timing, and a correctly applied cue — and when all three of those elements come together correctly the departure feels less like something you did and more like something that simply happened, which is exactly how it should feel. The departures that look and feel effortless from the saddle are the ones where the horse was organized before the ask, the cue was clear and well timed, and the rider's body stayed out of the way and allowed the transition to happen rather than interfering with it at the critical moment. Preparation is where most rough departures are lost before the cue is ever applied. The quality of the gait you are departing from — whether walk or trot — sets the ceiling for the quality of the departure. A sluggish, heavy trot will produce a late, scrambled departure. A tense, quick trot will produce a rushed, unbalanced one. What you want in the strides leading up to the ask is a forward, rhythmic gait with the horse light in your hand, responsive to your leg, and carrying himself rather than leaning on either the reins or the rider's leg for support. The inside bend in the last stride before the departure is one of the most useful preparation tools. A very slight flexion to the inside in the final stride positions the horse's body correctly for the departure — the inside hind leg is already positioned to step under the body, and the horse's weight is already very slightly shifted in the direction that makes the correct lead mechanically easier. The cue needs to be applied as a complete, coordinated package. Inside seat bone down and slightly forward, outside leg behind the girth to trigger the outside hind, inside leg at the girth to maintain bend and forward energy, outside rein steady to control pace, inside rein soft and yielding to allow the bend and forward reach. All of those elements applied simultaneously in the right proportions produces a clean departure. Your own stillness at the moment of the ask determines whether the horse can respond clearly. Close the aids, feel the horse step up into the canter, then immediately soften the hand, follow the new motion with the seat, and let the horse find his rhythm. Practice the departure, but not obsessively — five or six correct departures in a session, each one set up correctly and rewarded generously, will build a better horse faster than thirty hurried ones where the preparation is skipped and the result is forced.