Many people love water, but many babies may not. It can be jarring and startling to an infant - especially if they haven't been around it much and suddenly they're in the ocean where it's loud, salty, and splashes in their face and stings their eyes a bit. It can be helpful to introduce them to water slowly before taking the plunge (pun intended).
Getting a baby used to water is imperative. Knowing how to swim is a life-saving skill that everyone should know how to do, and it' easier to learn to swim if you aren't petrified of water because you've been in it hundreds of times and had positive experiences.
Plus, for most people, being around water is very calming (hence why beaches are so popular). Being in water is possibly even more soothing. Wallace Nichols, a marine biologist and research associate at California Academy of Sciences, calls it the "blue mind effect." The term is used to describe the "calm, peacefulness, unity, and sense of general happiness and satisfaction with life in the moment that people feel in and around water." According to Psychology Today, the effect may be because of catecholamine neurotransmitters, which relay stress signals in the brain. The transmitters recalibrate in water, and reduce to lower levels similar to the levels delivered by meditation. This reduces stress and anxiety (and makes you happy).
Swimming in a pool was our fourth step of introducing our baby to the water. The first three were regular baby baths, then putting him in bigger baths, and then I even did some breastfeeding in the bath to help strengthen that positive association with water.
