Papa’iloa Beach
This beach was really awesome, and pretty much deserted. It is down a quiet residential dead end road with beautiful houses, there is a small parking lot right across from the entrance (Papailoa Rd Haleiwa, HI 96712). Take the dark passageway out to the bright beach and there is a long stretch of gold sand and some rough waves.
You will feel like you are in on a great secret. I didn’t try swimming here, and the weather wasn’t great when we visited. We were looking for turtles, but it was late and there was not enough sun. We ran into one family here and started chatting with them. They said that turtles are always at the beach when it is sunny at the edge of a rock wall, and they love eating the green algae. 
So according to our new friend Norm you can go, pick the green stringy algae from the rocks and drop it off the ledge and the turtles will eat it. I am so let down that both of our visits to the northshore were rainy and we didn’t get to do this, but if you are visiting let me know if you see these turtles! Turtles or not, if you are looking to sunbathe this is a really quiet and scenic beach, just watch out for rocks.
Ehukai Beach
This is probably the most popular beach on the northshore because it is the ‘banzai pipeline’ (59-337 Ke Nui Rd Haleiwa, HI 96712). We accidentally visited during the Pipe Masters competition and saw some amazing surfers in action amongst the 20ft (at least!) waves. 
What a show! That being said this is definitely not a swimming beach, only experienced surfers should go in wild waters like this. It can be great for watching the action and sunbathing. It’s a huge beach with tons of space to find your own area. The sand is really porous and feels great under the feet, the water is a gorgeous color. There is a small parking lot or tons of unmetered street parking and facilities. Seeing these huge waves is a must-do on many itineraries when visiting Oahu.