Alexander & Baldwin Inc. tripled its third-quarter profit with greatly improved performances from its ocean transportation service in China and sugar business on Maui.

The Honolulu-based company reported today earning a net profit of $25.7 million, or 62 cents per diluted share of stock, in the July-September period, up from $8.5 million, or 21 cents per share, in the same period last year.

The big gain was largely from A&B’s ocean cargo subsidiary, Matson Navigation Co., which posted a 67 percent rise in operating profit to $40.4 million in the third quarter from $24.2 million a year earlier.

A&B said Matson’s performance was principally driven by higher volume and yields in its China service, which it expanded in mid-September.

Another contributor to the rise in profit was A&B’s Maui sugar subsidiary, Hawaiian Commercial & Sugar Co., which benefited from higher sugar prices and production.

HC&S, along with Kauai Coffee Co., delivered an $800,000 operating profit for A&B, which represents a $13 million improvement from a $13.8 million operating loss in the 2009 third quarter.

Operating profits from real estate leasing and sales were lower for A&B.