Blackett Strait is not a strait so much as a squeeze - the narrow passage where the central Solomon Islands pinch together, with Kolombangara's volcanic cone rising steeply to the north and flat Arundel Island hugging the south. In early 1943, this geography mattered more than almost anywhere else in the Pacific. The Japanese had built a seaplane base at Vila on Kolombangara's southern coast, and an airstrip at Munda on New Georgia, and they kept both supplied by sending destroyers down at night from their main fortress at Rabaul. American planners called the larger corridor the Slot. They called the nightly runs of Japanese resupply ships the Tokyo Express. Blackett Strait was one of its shortcuts home.

On the night of 5 March 1943, the destroyers Murasame and Minegumo had finished unloading at Vila and chosen the shorter return route through the Kula Gulf. They did not know that Rear Admiral Aaron Merrill's Task Group 68.5 - three light cruisers and three destroyers - was steaming into the same waters, tasked with shelling Vila's shore facilities. The Americans had SG surface-search radar; the Japanese did not. When the cruiser Montpelier's radar returns resolved into two fast-moving pips, Merrill's force already had a firing solution. The opening salvo straddled Murasame. Six salvos in, she was burning. The destroyer Waller fired five torpedoes and one found its mark. Murasame broke apart and went down before Minegumo's captain could finish giving orders. The Americans then shifted fire to Minegumo and sank her too, all before the Japanese could release a single torpedo in reply.

The bombardment of Vila proceeded as planned. American ships steamed away toward their base having lost not a man. For the Imperial Japanese Navy, which had dominated night battles in these same waters the previous year through superior optics and the lethal Long Lance torpedo, the engagement was a shock. Radar had changed everything. Over the next months, Allied aircraft began sowing mines throughout the northern Solomons - torpedo bombers planting steel fruit in the same passages the Tokyo Express needed to use. The strategic picture shifted. The Japanese could still reinforce Rabaul, but every run grew harder, slower, and costlier.

Five months later, in the same Blackett Strait, an American patrol torpedo boat idled with engines barely turning over, trying to keep her wake invisible to Japanese floatplanes hunting above. The destroyer Amagiri - returning from yet another supply run - came out of the darkness and ran her down. The PT boat was cut in half. The lieutenant commanding her, John F. Kennedy, gathered his surviving crew onto the shattered bow, then led them swimming to a tiny island. Two Solomon Islander scouts named Biuku Gasa and Eroni Kumana found them. Gasa and Kumana ferried a coconut carved with a rescue message through Japanese-patrolled waters, and the crew came home. Decades later, Kennedy would keep that coconut on his Oval Office desk. The man who found him lived in the Solomons until 2014.

Today Blackett Strait runs blue and calm between Kolombangara's forested slopes and Arundel's low green shore. Dive charters pass over the wrecks of Murasame and Minegumo; local fishermen know the spots. The villages along the shoreline remember, in the way small island places remember - through stories passed down, through the occasional rusted Japanese helmet pulled from a garden, through the fact that some of the elders were there. It is not a place you pass through without feeling the water has a longer memory than the land.