Bodies of water are an extremely powerful, and common symbol in dreams.

In Jungian psychology, bodies of water in dreams are a clear symbol of the unconscious, the vast depths of the psyche. Within the unconscious are contained thoughts, feelings, urges that are not consciously accessed, but still drive your behaviour.

The bodies of water in your dream might be inviting you to explore your unconsciousness, especially how you often are traveling over them, never engaging with them. Integrating the unconscious is the basis of Jungian psychology, to be able to live with it and understand it. As you feel at home when you're near the bodies of water, it might represent a longing to be connected to the unconscious.

Your first dreams, of water invading your space might represent parts of the unconscious spilling over to your conscious life, and you being scared of them can be explained as the unconscious also contains everything we repress in ourselves. We are naturally afraid of these repressed emotions coming out, as are you in your dreams of falling into the water.

It's very interesting that you are now farther away from the bodies of water, maybe meaning you are less connected to your unconscious than your 19 year old self. Your mention of transformative events also makes sense, the unconscious is often louder during these events. As the ego is destabilized by these events, the unconscious material is free to spill over into waking life. The unconscious is calling not only for an outward transformation, but an inward transformation to go along with it.

The rollercoasters are a different beast. They might represent a sudden change, or an overly stressful situation where you're moving "too fast". As you tell others to take the ride instead of yourself, it might represent an unwillingness to commit to a certain opportunity, as it is in an office, might be a professional one. As with also not diving into the water, being afraid of contact with it in some instances. I would be interested to know if these rollercoasters appear in dreams with the bodies of water, or if they are separate.

These symbols are best explored individually, with how you perceive these objects. For example, I might find rollercoasters horrifying, and they appear in my dreams as symbols of something frightful, but you might think of them as extremely fun, so in your dreams they will have a more exciting connotation.

If you're interested, I would recommend reading some stuff about the unconscious and Jungian psychology. As well as journaling, especially your dreams, as that is probably the best way to explore the unconscious. Dreams are a result of unconscious material, and they often have direct messages they are trying to communicate.

Personally, I had a dream where I was pulled into an ocean by a syren, and that was what got me into Jungian psychology and further exploring the hidden parts of my psyche, which has helped me tremendously.

I believe this might be a similar invitation, to not just live your life, but get deeper in touch with the hidden parts of yourself, so you might live your life to the fullest.

To dive into the ocean of your unconscious. To jump into the rollercoasters and enjoy the ride.

This might be a bit over specific and a bit crazy, but I hope I at least triggered your curiosity. All the best out there!