About 17km south of Trinco, there's a turn-off on the left for Marble Beach (signposted just before the Kinniya bridge), a glorious cove bookended by wooded headlands. Run by the air force, there is a resort at the north end of the cove. But spend your time at the south end in the perfect water, enjoying the emerald and blue views and the sight of the odd passing freighter. Note that on weekdays, it can get overrun by school groups.