The Pacific War is frequently characterized as a ‘race war’ and a ‘war without mercy’. The experience of Japanese prisoners on American submarines, however, suggests that hatred could often quickly be overcome once combatants spent time in close proximity. The confined space of submarines made a degree of interaction between prisoners and captors unavoidable. Through a series of case studies, the evidence suggests that submariners sometimes contravened the Geneva Convention in extracting work and obtaining information from prisoners. On the other hand, it appears that relations between prisoners and captors were for the most part amicable and at times mutually supportive. Although these relationships were manifestly unequal, occasionally prisoners exercised a degree of influence over submariners’ fates.