Question 1

Which Big Island beach has the cleanest water?

Accepted Answer

Hapuna Beach on the Kohala Coast consistently ranks among the cleanest beaches on the Big Island. The dry leeward coast, excellent ocean circulation, and resort-grade infrastructure contribute to reliable water quality. Mauna Kea Beach and the Kohala Coast resort beaches also rank well. Always check current advisories before swimming.

Question 2

Are Hilo beaches safe to swim?

Accepted Answer

Hilo Bay beaches have historically variable water quality. The Hilo area has high cesspool density, significant stream input, and frequent rainfall, all of which contribute to elevated bacteria levels. Beaches like Keaukaha and areas near the Wailuku River mouth are frequently under advisory. The Kohala Coast on the west side is generally much more reliable for water quality.

Question 3

Is the Kona coast or Hilo side better for water quality?

Accepted Answer

The Kona/Kohala Coast (west side) is significantly better for water quality. It receives far less rainfall, has better ocean flushing, and less stream input compared to the Hilo side. The dry conditions mean less runoff and fewer bacteria spikes. The Hilo side is one of the wettest areas in Hawaii, leading to frequent water quality issues.

Question 4

Does rain affect Big Island beach water quality?

Accepted Answer

Yes, dramatically — especially on the Hilo (east) side, which receives over 100 inches of rain annually. The 72-hour rain rule is critical. Even the normally dry Kona coast can see elevated bacteria levels after Kona storms. The Kohala Coast resort area is the most sheltered and least affected by rain events.

Question 5

Are there cesspools near Big Island beaches?

Accepted Answer

Yes. The Big Island has thousands of cesspools, with particularly high concentrations in the Hilo area and parts of Kona. Hawaiian Paradise Park and surrounding subdivisions in Puna have some of the highest cesspool densities in the state. Cesspool contamination via submarine groundwater discharge is a significant contributor to bacteria levels at east side beaches.

Safest Beaches on the Big Island for Water Quality

Top-Ranked Big Island Beaches for Clean Water