Schizm: Mysterious Journey (2001) by L.K. Avalon in collaboration with Australian science fiction author Terry Dowling.

As officially described:

Several exploration attempts of Argilus have failed to reveal the secrets behind it's mysterious abandoned condition - a developed planet with absolutely no people.

Previous exploration teams had reported unusual findings, prior to them mysteriously going missing themselves. Their garbled messages speak of a world containing large habitable organic vessels aimlessly floating and abandoned. These messages are the only legacy that remains of a missing race.

Now you must travel to the strange and exotic lands of Argilus, on a quest to uncover the secrets behind a strange phenomena. Here you will discover the mysteries and the secrets that, until now, have been lying dormant waiting to be revealed.