Redditors on r/SanDiego were baffled by a 387-foot-long yacht docked in their city. The OP posted a picture, asking who it belonged to. It didn't take long for users to crack the code.

The superyacht, named the Liva O, belongs to billionaire Stephen Orenstein.

Priced at $250 million, according to Luxury Launches, it has a "sizable marble-clad fireplace," a helicopter pad, a submarine, and a pool that "can be elevated and adorned with liquid marble emulating the sea's surface."

Commenters weren't pleased. Superyachts like these are incredibly detrimental to the environment. The wealthiest 10% of the planet (of which Orenstein is part of) contributes to half its pollution, and their use of superyachts only exacerbates it.

According to research reported by Fortune, "The annual CO2 emissions of the top 300 superyachts is almost 285,000 tons." When both sailing and docked, superyachts also cause light and noise pollution, disturbing the local wildlife.

Unfortunately, it's difficult to make something as large and energy-consuming as a superyacht sustainable. The Liva O, for example, uses a diesel-electric propulsion system. While hybrid motors can be eco-friendly on other vehicles, that's actually not the case with yachts.

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According to a study reported on by Yachting Monthly, electric and hybrid propulsion systems are worse for the environment than traditional internal combustion engines. The greenest option is reportedly to "switch to using sustainable synthetic or biofuels such as hydro-treated vegetable oil or e-petrol."

The Liva O's hybrid propulsion system seems to be a case of greenwashing — that is, pretending to use clean energy while doing anything but and continuing to contribute to the planet's warming climate. Critics argue the use of superyachts needs to be more heavily regulated, if not stopped altogether.

"Nobody should be this rich …" one user said.

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