Whales are participants in the cryptocurrency market, the largest coin holders.
It owes its name to the largest mammals. In addition, such traders can create a “wave” that affects the rate of a certain coin.
For example, a whale puts up for sale part of its crypto capital at a deliberately low price. The market begins to panic and the price of this cryptocurrency falls. Then the whale buys up the cheaper coins and recovers the exchange rate while remaining in the black.