This is my interpretation:
The first verse explains him floating down a river (river meaning life), oars freed long ago (meaning he has no control, which to me means death where we have no control of anything anymore). Lying face up on the floor of my vessel means to me that he is looking at things from a totally different perspective. We stand upright most of our lives. When we die, we are put to rest lying face up on the floor of a vessel (vessel meaning his body). When this happens and we are dead, we can see the true splendor of life because we are looking at it from a totally different perspective. This is why his heart begins to overflow as he marvels at the stars, because life is so BEAUTIFUL and he is appreciating it fully for the first time.
The second verse, I think, describes the emotional journey associated with "letting go" and leaving the shore and these perceptions of complete control, which in many ways and to many of us, has grown to the point of being our lover.
The final verse to me means that he will find a way to communicate with the living somehow when he says he is building an antenna and that transmissions will be sent when he is through (through to his final destination, which is open to interpretation, maybe heaven, maybe reincarnation). I imagine he aims to communicate through everything, as he was from the earth and now part of the earth, a permanent fixture of existence even though his previous physical form has changed. Maybe we can meet again further down the river means that in death he will reunite with his loved one/s, then they can share what they have discovered together and marvel in the view of existence itself. Such a beautiful picture in my head...
My favorite part of the song is right after the last words, where the instrumental starts playing. THIS STARTS AT 4:33 INTO THE SONG. To me, the song is saying much much more without words. The music is saying, "Goodbye, farewell. We will see each other again. Even though we are apart, we are together. I am with you in all things, in everything you do, in everything you touch, in everything you feel. I am life, as I came from the earth and now I am part of the earth and everything in it." The frogs in the end represent the simplicity of life, the peace when we listen.
