Hirokawa Maru (Bonegi I)

By November 1942 the fight for Guadalcanal had become a contest of supply, and Japan was losing it. In the aftermath of the naval battles of 12–15 November, Rear Admiral Tanaka's last four surviving transports abandoned any hope of unloading offshore and simply drove themselves onto the beaches west of the American lines to disgorge troops and rice directly. The Hirokawa Maru went ashore near the mouth of the Bonegi River on 15 November and was wrecked where she lay through the day by aircraft, field artillery, and destroyer gunfire before most of her cargo could be landed. Her bow has sat in the surf line ever since — snorkelers float over it — while the rest of the hull runs down the dark volcanic sand into deep water. Known to divers simply as Bonegi I, with her consort Kinugawa Maru (Bonegi II) beached minutes away, she is Guadalcanal's classic shore dive and a blunt monument to the campaign's arithmetic.

How she sank: Deliberately run ashore at Guadalcanal on 15 November 1942 to land troops and supplies, then destroyed by US aircraft, artillery, and naval gunfire.

Condition: Progressively broken from decades of surf at the shallow end; the deeper structure holds together better in still water.

Penetration: Limited. Open breaks in the hull allow short pass-throughs in the shallow and mid sections; the deep stern is dark, silty, and for experienced divers only. Entering any overhead environment requires specific training — a wreck certification at minimum, technical wreck training for full penetration.

Recommended certification: Open Water for the shallows; Advanced Open Water beyond the mid-hull

Current: Mild · Visibility: 8–20 m

Marine life: Corals and clams armor the shallow wreckage, anthias and damsels swarm the framework, and eagle rays and reef sharks appear off the deep end.

Hazards: Surge and surf at entry, sharp plating in the shallows, and a seductive slope that keeps offering another five meters of depth.

Lives were lost aboard and around her during the beaching and bombardment; she is dived respectfully. Solomon Islands wartime relics are protected — nothing may be recovered.

Wartime relics are protected under Solomon Islands law; take photographs only.