The busiest Costco warehouse in the world is not in New York or California but on the island of Oahu: the lone Costco in Iwilei, Hawaii, which routinely outpaces its peers by wide margins. Reports tracing back to the mid-2000s show the Iwilei store generating roughly $300 million in annual sales—more than double the roughly $120 million average per Costco—earning it a long-standing reputation as the chain’s highest-grossing location.
The store’s fame is as practical as it is numerical. Iwilei serves both as a standard Costco Wholesale and as a Costco Business Center, a dual role that broadens its customer base beyond typical household shoppers. Local business owners from hotels, convenience stores and gift shops use the warehouse to stock goods that are otherwise hard to source or expensive to ship to Hawaii. That commercial traffic, combined with steady demand from residents and the steady stream of tourists who flock to Oahu, keeps the aisles and parking lot crowded nearly whenever the store is open.
Hawaii’s retail landscape helps explain the Iwilei surge. The Iwilei Costco is one of only eight Costco locations across the state and faces limited competition—there are reportedly only two Sam’s Club warehouses on the islands. With fewer wholesale alternatives and relatively uniform pricing across Costco’s U.S. network, shoppers often rely on the Iwilei location to access staples at mainland-comparable prices, a valued resource during times of inflation or supply strain.
The store’s inventory also caters to its unique customer mix. In addition to bulk grocery and household items, the Iwilei warehouse stocks locally produced Hawaiian specialties and operates a fresh poke section, offering ready-to-eat options that appeal to both residents and visitors looking to sample island flavors. Those local touches, combined with the business-focused inventory, help explain why many shoppers make Iwilei their go-to Costco despite the crowding.
But the popularity comes with drawbacks: frequent congestion in the parking lot and long in-store lines have made the location notorious among some customers, placing it on lists of the most frustrating Costco experiences in the United States. Shoppers report that the sheer volume of traffic can make visits slow and difficult, even as they continue to patronize the store for its value and selection.
What began as an outlier in the mid-2000s has since become entrenched: the Iwilei Costco’s mix of geography, limited local competition, a business-oriented offering and tourist demand have combined to make it an indispensable—and exceptionally busy—retail hub in Hawaii.