Campus by the Sea, Christian retreat center in Gallagher's Cove, Santa Catalina Island, United States.

Campus by the Sea is a Christian retreat center on Santa Catalina Island with multiple buildings housing accommodations, dining areas, and meeting spaces for groups. The facilities support water activities and access to island trails.

Campus by the Sea was founded in 1951 by Mel Friesen and other InterVarsity leaders as a summer site for student discipleship. In early 1980 a flooded creek in the narrow valley washed eight cabins and buildings out to sea and destroyed the fresh-water plumbing. Volunteers and professional crews rebuilt that spring, adding the Lighthouse dining and multipurpose building, which first ran on a generator before three utility poles were installed.

The place is known for developing the Mark Study method, an educational approach to studying the Gospel of Mark. Original manuscripts that document this learning process can be found in the Crow's Nest library.

The center welcomes visitors year-round except from mid-December through mid-February. Activities include snorkeling, paddle boarding, kayaking, and exploring the island's hiking trails.

The camp's library, the Crow's Nest, opened in late summer 2006 and displays a copy of Paul Byer's original manuscripts of the Gospel of Mark, along with his teaching notes. Byer, a University of Southern California graduate and longtime InterVarsity staff member, originated the inductive method behind the Mark Study.