When you get off the water taxi in Fethiye, with your back to the sea turn left and walk along the prom towards Calis. Keep going until you reach Boğazici Restaurant, cross over the road and it on the other side next to the canal. About twenty minutes stroll. Alternatively you could get the Belediye Bus (blue bus) that leaves on the hour from Calis and get off right outside where there is a bus stop. Once the bus has turned onto the prom I think it is the first stop.