I would not advice you to even try that,take the shuttle.Central Florida parkway is pretty busy and not really pedestrian friendly,plus the SW parking lot is almost on the opposite side from Discovery Cove.Even though it's not a short walk I think walking to Aquatica is more doable as you only have to walk on Sea World drive which is right next to the parking lot and a lot calmer street that the Central Florida pkwy,you would still have to cross I-Drive but it's much more doable than trying to walk on Central Florida Pkwy to get to DC.I remember staying one time at the Hilton Garden Inn which along with the Rennaissance hotel are walking distance to Sea World,I remember just crossing Sea World dr and you're in the SW parking lot.