If a ship moves from freshwater into seawater, it will

When a ship moves from freshwater into seawater, it will rise a little higher. This phenomenon is explained by Archimedes' principle and the concept of buoyancy. Seawater contains dissolved salts, making it denser than freshwater [c3, c5, t4]. According to Archimedes' principle, the buoyant force exerted by a liquid is equal to the weight of the fluid displaced [t4, t8]. Since seawater is denser, a smaller volume of it is required to provide an upward buoyant force equal to the ship's weight compared to freshwater [c1, t5]. Consequently, the ship does not need to sink as deep to displace its own weight in seawater, causing it to float higher [t3, t9, t10]. This density difference is so significant that ships use 'Plimsoll marks' to indicate safe loading levels for different water types to prevent sinking when transitioning to less dense freshwater [t7, t9].

Sources

1. [1] Science ,Class VIII . NCERT(Revised ed 2025) > Chapter 5: Exploring Forces > Activity 5.13: Let us investigate > p. 76
2. [2] FUNDAMENTALS OF PHYSICAL GEOGRAPHY, Geography Class XI (NCERT 2025 ed.) > Chapter 13: Movements of Ocean Water > Characteristics of Ocean Currents > p. 111
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 32: Ocean Movements Ocean Currents And Tides > Secondary Forces > p. 487