Life on the water is getting a sleek new look.

Amsterdam-based +31Architects recently unveiled its designs for a series of houseboats that provide sophisticated accommodations while sailing throughout Europe. The vessels will be built by WSM Wohnschiffmanufaktur, a manufacturer in Germany.

The Naturecruiser is the smaller of the two, measuring 15 meters and starting at €535,000 (US$602,000). It can accommodate eight when cruising, and is perfect for weekend jaunts. The Waterloft is 24 meters, starting at €899,000. Up to 25 people can cruise on board.

Both have a slender, modern shape that is a cross between a houseboat and a ship, according to +31Architects. Each houseboat is fully customizable, both in terms of the layout and the amenities. Possible extras include an infrared sauna, an onboard hammam, whirlpool, kitchen island, and other amenities.

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Furnishings are also custom made, and designed with clients to their specifications. And the boats feature floor-to-ceiling windows on three sides, allowing guests and residents a view of the water outside at all times.

The vessels can be moored at a fixed berth in a marina, according to +31Architects. Or they can sail between Europe’s port cities and marinas via its lakes and rivers.

Furnishings are custom made, and designed to client specifications. +31ARCHITECTS and WSM Wohnschiffmanufaktur

The idea for the sustainable houseboats originated with Marcel Neugebauer, the founder of WSM Wohnschiffmanufaktur, who wanted to design a sailing home up to his own standards. His desire to live on the water sparked the design of the company’s houseboats.

At the same time, the boats had to have little to no impact on the environment. To that end, the vessels use solar panels and solar collectors fitted on the roof to generate power and heat water, making the houseboat virtually self-sufficient when docked in the marina.

Water tanks can be emptied when the boat is cruising, and it is equipped with hybrid electric drive for propulsion. The boat also includes a water purification system in which lake or river water can be cleaned on board, and wastewater can be treated on the boat as well.

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The aluminum hull doesn’t require the same toxic anti-rust coating that other vessels need every five to 10 years, and all building materials are chosen for their minimal ecological impact, according to the architecture firm. The propulsion is either diesel or battery electric with electric motor.

Prototypes are currently being created in Germany, and are expected to be completed by the end of 2019.

This article first appeared on Penta.