Despite all that water, there aren't too many harbourside restaurants in this area. Fortunately, Gantry is excellent. Try a wharfside table and enjoy views of Walsh Bay with a screen to protect you from sun and stickybeaks. The food, impeccably sourced from high-quality Australian producers, is delicious, with some standout fish usually on the menu and good vegetarian options.
It's also a bar; flopping down here on yacht-style seating on the edge of the wharf with a drink is a very pleasant Sydney experience.