Te Henga (Bethells Beach) is a west coast beach near Auckland, rated 4.8 from 253 Google reviews. No street address or opening hours are listed here. An earlier listing describes a local's guide covering how to get there, surf safety, the Lake Wainamu walk, black sand dunes and sunsets. Reviewers mention a sea cave, black sand, dunes, clifftop views, surfing, strong waves, plenty of parking and a lifeguard facility, and one notes the beach is not crowded.
On a west coast beach like this, the tide and surf matter most. Check tide times before walking to the cave, since high tide can cut off the way and mean wading, and swim only where it is patrolled and conditions are safe. Strong waves and rips are common on surf beaches, so keep children close. Wear sun protection, bring water and keep an eye on the weather. Take your rubbish home.
For a wild black sand beach and a sea cave near Auckland, Te Henga is a rewarding trip.