Answer:
Journey
Step-by-step explanation:
The word "expedition" in this passage means "journey." "Expedition" most often refers to a journey with the purpose of exploration and research. It often implies that there is someone unknown to be discovered, and therefore, it is often used to name adventurous and pioneering journeys. In this case, the author wanted to mount an expedition to find the Titanic, which means that he wanted to organize a journey to achieve this ground-breaking goal.