Why Japanese torpedoes crippled US cruisers

Why did US cruisers seem unusually vulnerable to Japanese torpedoes?

Surprise and straight-line movement increased the hits, while gunfire-oriented protection left some vital spaces vulnerable to torpedo damage.

Early-war tactical surprise exposed American cruisers to Japanese torpedoes while they were moving predictably or had been caught unaware. Their internal arrangements placed vital spaces deep in the hull to improve resistance to medium- and long-range shellfire. That choice left particular underwater spaces dangerously exposed when a torpedo struck in the wrong place. The example shows why cruiser design remained a set of compromises even when a navy spent heavily on protection.