(S (S (BASENP (NNP HMS) (NNP Tireless)) (VP (VBD was) (VP (VP (VBN submerged) (PP (IN under) (BASENP (DT the) (NN ice) (NN cap)))) (PP (IN at) (NP (BASENP (DT the) (NN time)) (PP (IN of) (BASENP (DT the) (NN incident)))))))) (PERIOD .))