ISA Sells a 73m Custom With an Underwater Room, Due 2030

What did ISA Yachts just sell, and to whom?

ISA Yachts announced on 23 September 2026 the sale of a fully custom 73-metre superyacht to an American owner, with delivery scheduled for 2030. Her defining feature, the Nemo Room, is a fully glazed observation space built into the hull below the waterline.

The Ancona-based yard, a brand of Palumbo Superyachts, says the project was developed entirely around the owner's own requirements rather than drawn from an existing platform. The layout accommodates up to 14 guests across six cabins, plus the owner's suite on its own dedicated deck, a specification more often reserved for yachts twenty metres longer. A crew of 22 will run the boat, and ISA says the internal circulation routes were designed specifically to keep crew movement out of the owner and guest areas.

Below the waterline sits the yacht's real point of difference. The Nemo Room uses expansive glazed surfaces to give guests a direct, unobstructed view of the surrounding water while the yacht is at anchor. Her interiors, including that room's fit-out, will be built by List AG, a specialist in bespoke yacht furniture making its third yacht with ISA after M/Y Okto and the 80-metre ISA Custom Belita, launched by the yard on 15 September.

Who designed ISA's new 73-metre, and why does that matter?

Exterior and interior design comes from the Dutch studio Sinot Yacht Architecture & Design, whose portfolio includes Azzam, still the longest yacht ever built at 180 metres, while naval architecture comes from Azure Yacht Design & Naval Architecture, the firm behind Oceanco's 88.5-metre Nirvana and the engineering on Damen's SeaXplorer expedition line.

This is the first time ISA has worked with Sinot on any project. The Dutch studio has more than twenty completed yachts between 16 and 137 metres to its name, built its reputation partly on Azzam, and unveiled its own concept for a submerged observation space, a 138.4-metre design called Inspire, at the 2024 Monaco Yacht Show. That concept placed its own Nemo Room roughly five metres below the surface. ISA's 73-metre is the first time a version of that idea has moved from a speculative concept toward a contracted, owner-commissioned build, two years after Sinot first proposed it.

Azure's naval architecture credentials sit in a similar bracket: Oceanco's Nirvana, the 85-metre St Princess Olga, and ongoing engineering work on Damen's SeaXplorer range, a line built specifically around long-range, high-latitude cruising. Giuseppe Palumbo, sole director of Palumbo Superyachts, called the pairing a source of great satisfaction, adding that Sinot, Azure and List are recognised leaders in their respective fields and that unique yachts come from exactly this kind of exchange of design cultures. For a yard historically built around its own in-house design relationships, reaching outside for a flagship-scale commission is itself a signal.

Has any other superyacht had an underwater viewing room before this one?

Fully or semi-submerged observation rooms already exist on a handful of yachts, most notably the 119-metre Motor Yacht A's glass-walled room with windows on both sides and the floor, plus semi-submerged lounges on Savannah and Elandess, but a purpose-built version sold on a fully custom 73-metre years before construction begins is rare.

Motor Yacht A remains the reference point: her observation room sits fully submerged with glazing on both sides and the floor, giving a genuinely enclosed underwater view rather than a window onto a moon pool. Savannah and Elandess both carry semi-submerged lounges, and Abeking & Rasmussen's 118-metre Project 8507 has a starboard-side Neptune lounge built on the same principle. The feature has become common enough across the industry that brokers and yards now use Nemo, Neptune and Aqua as near-interchangeable names for the same idea.

What makes ISA's version notable is not the concept itself but the sequence. Sinot put a version of this exact idea on a concept boat at Monaco in 2024 with no buyer and no yard attached. Two years later, the same design language has a contracted owner, a delivery date and a shipyard on record, ahead of Inspire itself ever being built by anyone. A submerged glazed room also carries real engineering cost that a rendering does not show: certified structural glass rated for hull pressure, additional sealing and maintenance access below the waterline, and a hull penetration that has to be designed around from the start rather than added later. ISA's announcement does not address class society or certification detail for the room, which a buyer evaluating a similar feature should ask about directly rather than assume.

Why is a yard best known for smaller yachts now building up to 100 metres?

The 73-metre sale is the latest step in a rapid scale-up ISA has run through 2026: the yard launched its new 80-metre flagship Belita on 15 September, unveiled the 82-metre Essence on 21 September as the third project in its Large Yacht Collection, and has a 100-metre custom project under construction, all inside about ten weeks.

ISA formally launched the Large Yacht Collection, its label for large tailor-made yachts, on 30 July 2026, and has moved fast within it. The 67-metre Sea Raider X, delivered as the yard's flagship in July, was superseded within two months by the 80-metre Belita, and Essence at 82 metres followed three weeks after that as the collection's third entry. The new 73-metre custom yacht announced this week sits inside that same run, and ISA's own release points to a 100-metre project already under construction as the top of its current range.

For a prospective buyer, the practical read is that ISA is scaling its custom capability in real time rather than presenting an already-proven large-yacht pedigree. Reaching outside its usual collaborators for Sinot and Azure on this specific commission, its first at this design pairing, suggests the yard is actively recruiting fresh talent to support that growth rather than stretching an existing in-house team across more and larger projects. That can mean more design variety across the collection, but it also means a buyer at 73 metres is trusting a size class ISA has not yet finished proving to itself at 100 metres.

What should a buyer considering a comparable custom order take from this sale?

A buyer weighing ISA against an established large-yacht specialist is looking at a yard moving quickly up the size curve with newly recruited outside design talent, at a price and specification that remain entirely undisclosed four years before delivery.

ISA's announcement, like the large majority of first-sale releases in this size bracket, publishes no price and no gross tonnage. Neither the yard nor Sinot has said whether the Nemo Room required any special class society approval, and no rendering of the room itself accompanied the release, an unusual omission for what the yard is presenting as the project's headline feature. A buyer evaluating a similar commission should ask a yard directly for the certification path on any below-waterline glazing before treating it as a settled specification rather than a design intention.

The rarity of the feature cuts both ways at resale. A genuinely distinctive room can separate a yacht from an otherwise crowded 70-to-80-metre custom bracket when she eventually comes to market, but it also narrows the pool of buyers who specifically want that feature, and it adds a component with no long-term maintenance record on a yacht this size. Combined with ISA's own size run still being mid-proof at 100 metres, this is a sale that rewards an owner betting on where a yard is heading rather than one buying purely on where it has already arrived.