Search engine users, when presented with multiple web search results, must be able to flexibly navigate dependent on the type of search tasks. Users who demonstrate inappropriate navigation behavior would likely fail to obtain target information. However, very few studies have examined users' web navigation patterns and their effectiveness in completing different types of search tasks in multi-layered hypertext environments. To fill these research gaps, we used data composing a sample of 1408 adults in the United States and the United Kingdom who completed both a specific information-locating task and an amorphous information-evaluating task when participating in the Programme for the International Assessment of Adult Competencies (PIAAC) 2012. We extracted participants’ clickstream data as well as their performance on the two tasks from recorded web navigation logs. Results from a series of latent class analyses and full-path sequence analyses showed five distinct behavioral patterns when participants performed the two tasks: of which, Flimsy, Breadth-first, Laborious, and Sampling patterns were revealed in both tasks, while the Satisficing pattern emerged exclusively in the specific information-locating task. Regarding pattern effectiveness, the Sampling pattern group outperformed other navigation pattern groups in the amorphous information-evaluating task, whereas the Satisficing pattern group performed best in the specific information-locating task.