Water as another job to excel at
Most Border Collies like swimming, and many like it the way they like everything: completely, obsessively and with unwavering eye contact while they wait for the next throw. The Border Collie is a herding dog bred to work sheep all day in hill country, reading movement and responding to whistles at distance. Put that brain beside a lake with a floating toy and the dog simply transfers the work ethic — the retrieve becomes the job, the swim becomes the outrun, and he will do it again and again without any sense that enough has happened.
There are exceptions. A Collie with little early water exposure may circle the bank, barking at a toy he wants but will not enter water for. Patient work — shallow entries, retrieving along the shoreline first, letting him follow a confident dog — usually unlocks it. But the common Border Collie problem at the water is not reluctance. It is excess.
The owner has to be the off switch
A fit Border Collie swimming retrieves is working hard: cold water, repeated sprints and constant excitement burn energy far faster than the dog's behaviour suggests. Collies are famous for hiding tiredness and even injury when they are locked onto a task, so the clock and your eyes, not his enthusiasm, decide when the session ends. Work in short sets — a handful of retrieves, then out for a drink, a shake and some calm lead walking — and finish the whole session while he is still fresh enough to settle afterwards.
Watch for the signs that focus is tipping into over-arousal: fixed staring at the toy, whining that will not settle, snapping at splashes, or swimming patterns getting frantic rather than smooth. Those are cues to end the game and do something boring for a while. A Collie who practises frantic water sessions rehearses frantic behaviour generally.
Coat, ears and water choice
The Collie's dense double coat handles cold water well but carries a lot of it home. Rinse after lake and sea swims, dry thoroughly — particularly in cool weather, when a wet Collie travelling in a cold car can chill — and check ears after regular swimming for the head-shaking and scratching that suggest trapped water is irritating the canal. Choose swimming water with the same care as for any dog: no strong currents, no algae blooms, a bank he can climb out of anywhere along his swim, and no fishing lines or hooks near popular spots.
Be thoughtful about wildlife and livestock around farm ponds and reservoirs. A herding dog who spots sheep or ducks from the water may try to work them, and that creates problems swimming skill cannot solve. Keep a lead on until you are sure of the setting.
Channelling the drive properly
If your Collie lights up for water retrieving, organised outlets suit him better than endless casual throwing: dock-diving, water retrieve training and canine swim clubs all give the drive rules, turns and an ending. Structured activity also protects his joints and brain in a way free-for-all sessions do not. To look for clubs and swim facilities that work with high-drive dogs like these, KinsLe Pet Services Directory lets you search what is available near you.