Swimming and diving are important aspects of movement bionics. Our eighth volume under the motto "Ask Nature" provides a vivid introduction to this mode of transportation in water and presents numerous examples of adaptations from nature that are significant for the development of watercraft. The focus is on historical perspectives, physical principles, and interesting biological as well as technical facts. Notable researchers and inventors showcase their discoveries and technical designs, demonstrating how exploration and invention can be conducted purposefully and systematically through the use of methods. Exciting experiments and simple, replicable models enhance the functional understanding of movement possibilities in and under water.