Do sharks always follow ships around? Not really. Ships travel far too quickly for sharks to keep up with them. A shark may be able to briefly hit the speed of a modern ship, but certainly cannot sustain that speed.

Contrary to popular urban legends, sharks do not "follow" cruise ships in the way they might follow small fishing boats. Sharks are primarily attracted to vibrations and the scent of blood or bait. Modern cruise ships are massive and produce significant noise and underwater vibrations that are more likely to deter most marine life than attract it. Furthermore, international maritime laws strictly prohibit the dumping of food waste or trash into the ocean near coastlines, which removes the primary "attraction" that might have drawn sharks in the past. While you might occasionally see a shark from the deck, especially when the ship is near a reef or a known feeding ground, they are not trailing the vessel across the open ocean. Sharks are energy-conserving predators and would find it physically impossible to keep pace with a ship traveling at 20 knots for an extended period just for the slim hope of a meal. Most "sightings" from cruise ships are actually dolphins or large fish like tuna jumping in the ship's wake.