Why is the water at Nusa Dua and Melasti beach in Bali sometimes murky with rough waves?

At Nusa Dua, swimming conditions aren't perfect: at high tide waves often break through the reef and reach the shore along with debris, at low tide it gets shallow in spots, and the best window is in between tides. Melasti is different — a rocky, scenic open-ocean beach without a protective reef, so it sometimes has big powerful waves; it's less ideal as a home base but worth a visit, and it's not far from Nusa Dua.

Some visitors report that in autumn more debris washes up on the beach and the waves become less swimmable.

At the main part of Melasti beach the waves were strong, but near low tide and further along the beach the water gets much calmer and clearer — the tide makes a big difference.

Over 6 nights at Nusa Dua, conditions were different every single day — from murky waves strong enough to knock you off your feet to perfectly clear water. You can't judge the beach based on just one day, it changes fast.

On some beaches the murky water isn't due to pollution — it's caused by yellow sand stirred up by strong waves. The beach itself stays clean, the water just doesn't look transparent.