Answer:
The sentence contains a gerund.
Step-by-step explanation:
A gerund is formed by adding -ing to a verb. It is important to understand that a gerund may look like a present participle, which is also formed with the addition of -ing, but the gerund functions as a noun.
In the sentence we are analyzing here, what we have is actually a gerund phrase, which consists of a gerund and modifiers: "biking along the shoreline." Notice that the whole phrase functions as a noun; in this specific sentence, it is the subject → What is one of my favorite hobbies? Biking along the shoreline.