From the pool at the Grandstand area of SSR, it is 0.216 miles to the boat ramp below the Carriage House. It will drop you off at the Westside of DS. If you want then you can take another boat to the Marketplace or Pleasure Island dock.
Or you can take the internal bus to the Congress Park section and walk across to Disney Spring Marketplace. Which is 0.311 miles from the CP bus stop.
I understand there is still a bus to DS from SSR as well.