The mill site sits on Kealohanui Street, a short turn off Farrington Highway, and it is open in the sense that a light industrial estate is open — you drive in, park in the yard, and walk.
The North Shore Soap Factory occupies the old mill tower and is the anchor. Soap is made on the premises, the stamps are cut in front of you, and it is the rare visitor-facing business on this coast that is actually a factory rather than a shop pretending. Island X Hawaii operates in the adjoining buildings with local crafts, coffee tasting and a shop that sprawls.
Around them are the working tenants. This is one of the places on Oʻahu where surfboards get shaped and glassed, and if a unit's roller door is up you can see it happening. There are mechanics, a furniture maker, storage, and businesses that do not want visitors and are not signed.
Outside sit the remains: the smokestack, sections of mill machinery, rail, and the wide concrete yard where the cane came in. Nothing is labelled. Nobody will stop you photographing it.
A farmers market has run at the mill on Saturday mornings for years, with produce, prepared food and crafts from Waialua and Mokulēʻia growers. Market days and times do shift, so check before making a special trip.
Allow forty-five minutes. It is not large and it is not polished, and that is the interest.