Final answer:
The amplitude of the wave is 2 m.
Step-by-step explanation:
The amplitude of a wave is the maximum displacement of a particle from its equilibrium position. In this case, the crest of the wave measures 2 m above the still watermark in the harbor. Since the crest is the highest point of the wave, the amplitude is equal to the height of the crest above the equilibrium position. Therefore, the amplitude of the wave is 2 m, elucidating the extent of the particle's maximum excursion from its resting point. Understanding this amplitude provides insight into a wave's strength and potential impact, crucial in assessing its behavior and implications in marine environments or other wave-related studies.