Final answer:
The gerund in the sentence is 'hiking', and it acts as a direct object following the verb 'enjoyed'.
Step-by-step explanation:
In the sentence 'Niko enjoyed hiking in the Sangre de Cristo Mountains', the gerund is the word 'hiking'. A gerund is a verb form ending in -ing that functions as a noun in a sentence. In this case, 'hiking' is used as a direct object following the verb 'enjoyed', thereby indicating the activity that Niko enjoyed. Gerunds can perform various functions in a sentence, such as the subject, direct object, subject complement, or object of a preposition.
A gerund phrase includes the gerund itself plus any modifiers or objects associated with it. For this sentence, 'hiking in the Sangre de Cristo Mountains' could be considered a gerund phrase, with 'in the Sangre de Cristo Mountains' acting as a modifier providing additional information about the activity.