马力欧(克里斯·帕拉特 Chris Pratt 配音)和路易吉(查理·戴 Charlie Day 饰)是生活在布鲁克林的两名水管工,他们刚刚成立了自己的小公司,但很显然,他们的家人并不完全支持兄弟两人的这份事业。某日,在工作中,马力欧和路易吉被水管吸入到了一个光怪陆离的世界之中,两人在旅途中被迫分开,马力欧来到了由碧姬公主(安雅·泰勒-乔伊 Anya Taylor-Joy 配音)统治的蘑菇王国,而路易吉则不幸的被传送到了由酷霸王(杰克·布莱克 Jack Black 配音)统治的库巴王国。
此时,酷霸王正准备大举进攻蘑菇国,掳走公主并和她结婚,在这个节骨眼上,马力欧的出现带给了碧姬公主希望,她带着马力欧来到了丛林王国,请求那里的国王和王子(塞斯·罗根 Seth Aaron Rogen 饰)的支援。
The Octopod is grabbed by a colossal squid. The Octonauts are unable to break free due to the hooks on the ends of the squid's tentacles. Fortunately the arrival of some sperm whales turns the squid from hunter to hunted.
Kwazii and Dashi become entangled in a strange deep-sea creature - a siphonophore - and when a geyser blasts it toward the surface, the Octonauts must stop its ascent before it fatally bursts.
A dangerous tidal wave washes all the fish up in the trees, which is also a big problem for the poison dart frogs who don't have enough puddles up in the trees for the tadpoles. Luckily, Tweak's new Gup-H is ready to help.