After the Titan submersible imploded last week, Matthew Gavin Frank’s journey to the depths with Karl Stanley, a friend of Stockton Rush’s, took on a new meaning. (Frank rode in Stanley’s sub in February of this year; his essay, in which Frank meditates on the eternal dangers and allure of deep-sea exploration, went online the day after the OceanGate sub went missing.) He discusses Stanley’s warnings to Rush, mass fear, and whether he regrets his experience.