Edgar Rice Burroughs 
Pirates of Venus 
Venus Book 1

Carson Napier set out for Mars in a secret interplanetary rocket but found himself instead on a different world — the cloud-hidden planet of Venus. Venus was a startling world — semi-private, semi-civilised. It was a place of unmapped oceans dotted with great islands; a world whose trees pierced the clouds and whose cities squatted on their branches; a planet whose inhabitants included men, half-men, and monsters, all struggling with each other for dominance.