The bay at Kealakekua is so translucent, so placid, that scores of novice snorkelers slip into the water daily, arriving by boats from Kailua-Kona, which anchor, bobbing peacefully, just beyond the obelisk that marks a far more violent episode in Hawaiian history. It was here that the great navigator Captain James Cook was killed on February 14, 1779.

Cook and his crew had sailed through the Hawaiian Islands little more than a year earlier when they anchored off Kaua'i to re-provision his flagship Resolution and a smaller vessel, Discovery. This was Cook's third Pacific voyage, but his first to explore the North Pacific. It was the voyage that earned him credit as the first westerner to discover the Hawaiian Islands.

When the British ships...