1. The problem statement, all variables and given/known data Two ports along a coastline are 300 km apart. One port has high tides 30 minutes later than the other. How deep is the effective depth for the tidal propagation? 2. Relevant equations I am thinking I need the following equation: V = square root (g*H). V = velocity. g = 9.8 m/s^2. H = the depth of tidal propagation. 3. The attempt at a solution I calculated the velocity (300 km/ 30 min = 167 m / s). Then I entered that into the equation, V = square root (g*H). I got H = 2845.8 m. I am wondering if this is the right approach for this problem. It seems too simple.