Note: indicated routes are approximate. Use official topographic maps for navigation.
The Light-to-Light walk in Ben Boyd National Park just south of Eden NSW is an easy three day walk south along the coast to Green Cape. I did it as a six day return walk, which gave me an excuse to stay in the bunkhouse at Green Cape, avoided having to organise transport back from Green Cape, and amortised all the costs and organisational overheads over six days instead of three.
The entire walk from north to south could be done as a two day walk, but what's the rush? By taking three days you avoid having to camp at the drive-in paid campsites and have more time for swimming, taking photos, birdwatching or whatever.
I did it in April and the ocean temperature was easily warm enough for swimming, although that will probably vary from year to year. There's a great little beach at Mowarry Point.
While you can camp at the paid campgrounds at Saltwater Creek and Bittangabee, they are reasonably expensive for what they provide for bushwalkers, can be busy and are aimed at car campers. You're better off camping at the walk-in campsites at Mowarry Point and Hegartys Bay. There are small creeks at both of those free campsites but they may dry up in summer or after long dry periods. Check with the Merimbula National Parks and Wildlife Service office on current conditions just before you start the walk. Walk with enough water to get you to the next paid campground just in case the creeks are dry and you have to continue on.
Looking back to Boyd Tower from Mowarry Point
At Mowarry Point you can camp on the the grassy headlands on either side of the beach. The water supply here is the small creek that you cross before climbing up to the headland above the northern end of the beach.
At Hegartys Bay there are sites on either side of the creek. The northern ones are more sheltered but not particularly level. There are a couple of sites just south of the creek that are probably more level but a bit more exposed.
In dry times you'll either have to camp at Saltwater Creek and Bittangabee, which have water tanks, or walk with enough water for an overnight stay at Mowarry Point or Hegartys Bay and a few hours the following morning before replenishing at the next paid campground. Check with the Merimbula NPWS that there's water at Saltwater Creek and Bittangabee, The paid campgrounds have toilets and gas barbeques. There are no facilities of any kind at Mowarry Point and Hegartys Bay
Light-to-Light Camps provided my transport between Eden and Boyd Tower. They're friendly, prompt, informative and provided a reasonably priced service. They also run fully supported walks. See their website for details. Highly recommended.
The official NSW National Parks and Wildlife Service Light to Light walk page is here