The Manly ferry leaves from Circular Quay Wharf 3, a short walk from the Opera House finish, and takes about 30 minutes. It is a working commuter service rather than a tourist boat, and it is also one of the better views in the city included in the price of an ordinary transport ticket: the harbour opens out past Fort Denison, the Heads close in on either side, and North Head appears ahead before the ferry turns into Manly Cove. Services run roughly every 30 minutes through the day; there is no need to book ahead.
Manly Cove sits on the harbour side of the peninsula, and The Corso, a pedestrian strip lined with cafes and takeaway food, connects it to the ocean beach in about five minutes on foot, flat the entire way. Manly Beach itself is a long stretch of sand backed by a promenade with a Norfolk Island pine treeline, built for walking rather than for the coastal stairs and headland scrambles that define Sydney's more strenuous beach walks.
For legs that ran a marathon the day before or the day itself, the promenade is the excursion, not a launch point for something harder. The full Manly to Spit Bridge walk is a genuine bushwalk with steps and exposed sections; the shorter stroll to Shelly Beach at the northern end of the main beach is a better match for the day, flat and shaded, ending at a sheltered cove with a café terrace.
The Corso and Manly Beach
The Corso connects the ferry wharf to the beach and carries most of Manly's café and takeaway trade: fish and chips, poke bowls, coffee that meets central Sydney's standard without the central Sydney queue. Manly Beach itself runs for roughly 1.5 km, framed by ocean pool at the southern end and the walk to Shelly Beach at the northern end. Swimming is possible year-round, though a race weekend in late August lands water temperatures in the high teens, cool rather than inviting for anyone not already used to it.
Shelly Beach
The walk from the main beach to Shelly Beach takes about 15 minutes along a flat, tree-lined path with the ocean on one side. Shelly Beach itself is a sheltered, calm cove, better for a swim than the open beach if the surf is up, and has a café terrace directly above the sand for a slow lunch with a view rather than a queue.
Getting back
Return ferries run through the evening from the same Manly Cove wharf, back to Circular Quay in about 30 minutes. There is no need to time the return precisely; the frequency of the service is the whole point of the excursion.