We all had pretty dark tans while growing up on Oahu. Of course, no one wore sunscreen. Today I never go outdoors without it and haven't for decades. In Hawaii, the sun can beat down on you even if you're outside for just a bit. I'm particularly careful with my face. Even with a good strong sun blocker, you will still tan.
Interestingly, I never burned as a child. I wasn't alone. Most of my friends got natural tans despite the state's extreme year-round UV index. I have higher melatonin I think than the average person. Plus, daily ambient exposure allowed us to maintain a constant "base tan." Fact is, we spent hours swimming or surfing each and every day. But the fact also is, no matter how much melatonin you may have, you can still get skin cancer. So do what I do; use it daily. Just be sure to choose one of the "reef-friendly" sunscreens when you're in the islands. Everything else is illegal.