Even if there is a drop of blood many miles away, its smell reaches the nose of the shark - this information is completely baseless, it can be called an exaggerated description. Explaining in detail how we smell may help explain why this information is irrational.
When we smell something, it means that tiny particles from the corresponding substance are connecting to our nasal chemoreceptor. Let's see how sharks smell under water.
Sharks do not have a nose or nostril like us, instead they have a nostril like organelle called nare. Inside the navel is a layer of skin covered with numerous sensory cells, called "olfactory lamellae". It is connected to the tiny particles of the odor-producing substance. Although they vary from species to species, a large part of shark brains are responsible for their sense of smell.
However, this strong sense of smell is not only significant in sharks, but also in many species of fish.
The shark, under the influence of its strong olfactory power, can not only perceive the existence of prey, but can also form an idea of the exact direction in which the prey is present. But that's not the end of it, the shark can use their strong sense of smell to return to their home. Currently, with global warming and climate change, ocean chemistry is changing rapidly, and as a detrimental effect, sharks' ability to navigate and hunt is declining significantly.
However, back to the answer to the original question. Exactly how far a shark can smell something depends on the species of shark and the nature of the ocean. However, it can be said with certainty that even sharks can easily smell from a distance of 100-300 meters.
