Final answer:
The gerund in the provided examples is 'swimming,' which is used as a noun functioning as the object of the verb 'pause'.
Step-by-step explanation:
The book Salt to the Sea does not appear in the provided excerpt. However, the concept of a gerund is illustrated in the example sentences given. In the sentence, 'He did not pause swimming to inquire what manner of current had caught him,' the word 'swimming' is a gerund as it is an -ing form of a verb functioning as a noun. Here, 'swimming' acts as the object of the verb 'pause,' which is a role typically filled by a noun or a noun phrase.