Call it the Peloton of the pond. Hydrow combines a burly electromagnetic-resistance rowing machine with a 22-in. touchscreen and a web connection. That allows home scullers to train with real-life instructors and teams all over the planet, with interactive workouts set in famed bodies of water—from the Charles to the Thames. Boston-based rowing coach and entrepreneur Bruce Smith dreamed up the Hydrow in 2018, intending to bring onto dry land the feeling of rhythm and synchronicity that you experience rowing with a team. The recent fervor for at-home workouts has provided Hydrow with a tailwind: sales of the machine, which retails for $2,245, surged some 400% from January to April.