Spinnaker Watch - Croft Mid-Size Automatic Dolphin Project Limited Edition - SP-5177-22 - Dolphin Cave

Spinnaker Croft Mid-Size SP-5177-22 Dolphin Cave – Dolphin Project Automatic Watch, 425 Pieces, Green Dial, Luminescent Dolphins

Dolphins know their territory. Not just the open water where they hunt and travel, but the specific features of the seafloor and coastal landscape that define their range — the seagrass meadows, the thermal currents, and the underwater caves and rock formations that serve as shelters, play spaces and nurseries. A dolphin cave is not a dark, empty place. It is an active environment, filtered with the particular green-tinted light that penetrates to that depth, populated with the small organisms that dolphins find there, and known to the pod in the same way a neighbourhood street is known to its residents.

The Spinnaker Croft Mid-Size Automatic SP-5177-22 Dolphin Cave places that environment on the wrist. A deep green dial with a textured wave-pattern surface and luminescent dolphins. A green bezel that extends the colour to the case edge. 425 pieces produced — the smallest run in the Dolphin Project collection, making this the rarest of the three colourways. And 10% of net sales going directly to the Dolphin Project, the non-profit organisation that has been working to protect dolphins worldwide since 1970.

The Physics of Underwater Green – Why This Colour Belongs Here

The colour of the underwater world is determined by physics. Seawater absorbs different wavelengths of light at different rates: red is absorbed within the first few metres, orange and yellow follow, and what remains at depth — what actually reaches the eyes of a dolphin exploring a cave at thirty or forty metres — is predominantly blue and green. In coastal waters with suspended organic matter, the phytoplankton and algae that characterise productive marine ecosystems shift the ambient light further toward green, giving inshore reefs, seagrass beds and rocky coastal caves their characteristic jade and emerald tones.

The green of the Dolphin Cave dial is that light — not the surface blue of the open ocean, not the turquoise of shallow tropical waters, but the deeper, cooler green of a habitat rather than a seascape. It is the colour that a dolphin sees when it navigates a familiar underwater space in its home range, filtered through metres of water and the photosynthetic life that fills productive coastal ecosystems.

425 Pieces – The Rarest Watch in the Dolphin Project Collection

The production figures across the Dolphin Project collection are not uniform. The Aqua Play was limited to 500 pieces. The Dolphin Cave is limited to 425 pieces — a production run that is 15% smaller, at the same price point, with the same technical specification. For collectors who track production numbers, this distinction is meaningful: the Dolphin Cave is objectively harder to find, will represent a smaller proportion of secondary market availability once primary stock is exhausted, and carries a rarity argument that the other colourways in the collection cannot match.

Every one of those 425 pieces contributes 10% of its net sale value to the Dolphin Project's fieldwork. The organisation operates in Japan, South Korea, Mexico and other countries where dolphin hunting and captivity practices continue, and the funding generated by this collection directly supports those campaigns. The Dolphin Cave is the watch in this series where the combination of rarity and conservation impact is most concentrated.

Green Dial with Bioluminescent Dolphins – Day and Night in the Cave

The green wave-pattern dial of the SP-5177-22 shares its textural architecture with the Aqua Play — the relief-worked surface that replicates the rhythm of ocean water, the group of dolphins navigating the dial — but changes everything about the visual experience by shifting the palette from surface blue to depth green. The dial reads as more enclosed, more atmospheric, more like the interior of a space than the surface of a body of water.

After dark, the Swiss Super-LumiNova treatment on the dolphins and indices introduces the concept's most resonant dimension. In the deep ocean, bioluminescence is one of the most extraordinary phenomena on the planet: an estimated 76% of all marine species produce some form of their own light, from the photophores of lanternfish to the glowing bacteria that colonise deep-sea organisms. Inside an underwater cave, bioluminescence from the organisms that live in it can be the only light source. The luminescent dolphins on the Dolphin Cave dial glow in darkness with exactly that quality — light that does not come from outside, that belongs to the environment itself, visible only when the ambient light has gone.

Green Bezel, 316L Steel Case – Unified Colour, Marine-Grade Material

The green bezel of the SP-5177-22 extends the dial's palette to the case boundary, creating a visual continuity from centre to edge that the Aqua Play's blue dial against a neutral bezel does not achieve. The entire face of the watch — dial, indices, bezel — occupies the same chromatic register, producing a unified immersive effect rather than a contrast. The 40 mm 316L stainless steel case, at 14.1 mm thick and 47 mm lug-to-lug, provides the frame for this composition in the marine-grade alloy selected for its resistance to the saltwater environments this watch is built to inhabit. The screw-down crown seals the case for the 150-metre / 15 ATM water resistance rating that allows the Dolphin Cave to go where its name suggests it belongs.

Miyota 8215 – Self-Sufficient in the Dark

The Miyota 8215 automatic calibre — 21 jewels, bidirectional rotor, 21 600 vph, 42-hour power reserve — requires no external energy source. It winds through wrist motion and sustains itself as long as it is worn. In the context of a watch named for an enclosed underwater space where external light and surface conditions are irrelevant, the automatic movement's self-sufficiency carries an additional layer of thematic appropriateness: a mechanism that keeps working in the dark, drawing on its own stored energy, indifferent to what is happening on the surface.

Grey rPET Strap – The Ocean Floor's Colour

The included grey rPET strap — fabricated from recycled plastic — differs from the blue rPET of the Aqua Play in a way that reflects the Dolphin Cave's distinct environment. Blue belongs to the water column; grey belongs to what lies beneath it. The rocky substrate of underwater caves, the sandy and gravelled floor of coastal habitats, the weathered limestone and basalt that dolphins navigate by echolocation in their home range — all of these are grey. The grey rPET strap extends the Dolphin Cave's environmental colour palette from the dial to the wrist contact, completing a coherence that runs from the materials the strap is made from to the colour it carries.

The eco-responsible packaging maintains this commitment throughout the unboxing experience, ensuring that the watch's conservation credentials are expressed at every level of its production and presentation.

Why the SP-5177-22 Dolphin Cave Deserves a Place in Your Collection

425 pieces — the scarcest watch in the Dolphin Project series

At 425 pieces, the Dolphin Cave has a smaller production run than any other colourway in the collection. For the same investment and the same technical watch, this colourway offers greater rarity — a consideration that carries increasing weight as the initial stock is absorbed into collections and secondary market supply contracts.

The green that belongs to the depths, not the surface

The Dolphin Cave occupies a visual register in the Dolphin Project collection that neither the Aqua Play's blue nor the Sunrise Splash's warm tones can access: the deep, filtered, inhabited green of underwater spaces where dolphins are most at home and least observed. It is the most scientifically grounded colour choice in the collection, and the one that most directly evokes the environment that the Dolphin Project exists to protect.

Bioluminescent dolphins at night — the cave's own light source

The Super-LumiNova dolphins on the Dolphin Cave dial glow with a quality that, in the context of an underwater cave, is not merely decorative — it is the most accurate representation of what light looks like in that environment. A watch that glows from within after dark, referencing one of the ocean's most extraordinary phenomena, is a watch worth looking at twice in the same day.

The Spinnaker Croft Mid-Size Automatic Dolphin Project Limited Edition SP-5177-22 Dolphin Cave is available now at Minutimer. Discover the full Spinnaker collection, our range of limited edition watches, and all automatic watches in our catalogue.