Personal watercraft and watercraft power systems that include a power pod for supporting a power plant and a propulsion unit. An engine or an electric motor and a pump assembly are enclosed in the power pod. One or more sponsons removably cooperate with the power pod via a mechanical interface, such as dovetail joints and/or interlocking channels, formed between the power pod and the respective sponsons. A plurality of tool-lessly operable mechanical interfaces, locking mechanism(s), and fluid or electrical signal connectors allow the sponson(s) to be selectively secured to the power pod such that the resultant watercraft is modular and transportable by a single person when necessary.