This study investigates four representative Shinsui Parks—urban waterfront linear parks in Japan—located in Tokyo, by integrating social media data and eye-tracking experiments. Combining subjective public expressions and objective visual attention, the research explores park use patterns and landscape perception. Results reveal that during the COVID-19 pandemic, these parks continued to support daily activities. Natural elements attracted more visual attention and received higher ratings than artificial structures. While correlations exist between social media content and eye-tracking data, some frequently viewed elements were not reflected in online expressions. This study demonstrates that combining social media data and eye-tracking offers a complementary approach to understanding linear green spaces and provides methodological insights for urban park planning and design.