Nautilus Under Sea

The Nautilus Under Sea is the former Undersea Hunter of Cocos Island fame. This brave small ship is one of the most loved dive boats in the world with a huge reputation and following. The Under Sea underwent renovations in 2016 and gained a full-width superstructure and premium suite on the upper deck. She is a 90-foot liveaboard originally built in Florida in 1968 for Perry Oceanographic as a submarine support vessel, working primarily in the Bahamas and the Caribbean. The boat is now completely refurbished for serious diver comfort while maintaining its vast fresh water tank – never a shortage of hot and cold water, even on longer voyages!

The excellent vessel has seven cabins for the maximum of fourteen passengers. All cabins have private bathrooms, plenty of storage, 110-volt outlets, portholes and individually controlled air-conditioning. Five of the cabins have a queen-size lower and a twin-size upper, one has upper twin and a lower twin, and one – the only one on the main deck, the rest are on the lower deck – a queen-size lower.

The large dive deck is also convenient for swimming, kayak launching and, at night, shark viewing. There is a dedicated camera and dive gear storage for each diver, and the very large dive deck turns into barbecue under the stars. The partly covered sun deck is perfect for relaxing. The airy and light-filled dining area and the adjoining lounge are made for socializing and enjoying the excellent food onboard. Nautilus Under Sea offers free Nitrox and Rebreather Support.

Nautilus Under Sea Specifications

  • 95' x 24' ocean-going dive boat
  • Steel with teak deck
  • Engines: Twin Caterpillar 240 HP
  • Tenders: One 25ft. heavy duty fiberglass dive boat. One 32 ft. custom high speed aluminum dive skiff.
  • Generators: Two 65kW + 1 emergency genset
  • Voltage: 110/208 VAC 12-24 VDC
  • ISM safety certified audited by Bureau Veritas, VSAT, Satelite Phone
  • Compressors: 2 x water cooled Coltri MC-30
  • Full oxygen, nitrox and rebreather service
  • 19 guests, six staterooms, one quad stateroom, one premium cabin.

Lower deck

6 staterooms on the lower deck.

UnderSea Lower Deck Floor Plan

Main deck

Main lounge and dining room, dive deck, water level platform, ADA compatible stateroom, and triple stateroom.

UnderSea Main Deck Floor Plan

Sun Deck

Sun loungers, al fresco lounge, bar, hot tub and premium suite.

UnderSea Sun Deck Floor Plan

For over 25 years, Socorro's giant mantas have been interacting with divers in intimate encounters that are often the dive of a lifetime. These consistent up-close interactions with both chevron and jet-black mantas are unique in the world.

In recent years, we discovered a pod of dolphins that love interacting with divers as much as the mantas. Imagine a fully grown bottlenose dolphin swimming up to you in open ocean and touching you with a pectoral fin!!

Socorro has also become known for humpback whale encounters, 10 kinds of sharks including schooling hammerheads and silkies as well as whalesharks, white tip reef, silvertip and galapagos sharks.

Day 1

Arrival in San Jose Del Cabo. Meet up and enjoy the hospitality suite of the beautiful El Ganzo hotel. Boarding your ship after 8:00 PM. Sailing time at 9 PM.

Day 2

Spend the day unwinding at sea as the vessel heads to Socorro. Evening arrival at San Benedicto Island.

Activities:  Safety Briefing Diver Orientation Manta 101 Cocktail Hour!

Day 3

What you’ve been waiting for - Diving Day! San Benedicto is home to the friendliest giant mantas in the world! Activities:  4 dives Our famous Mexico taco Fiesta on the upper deck Manta ID

Day 4

Dive at Socorro Island.  Night snorkel with Silky Sharks. Activities:  3 dives + Snorkeling with silky sharks under flood lights Manta ID

Day 5

Dive at Socorro Island. Activities:  4 dives Shark Behaviour Manta ID

Day 6 + 7

Dive at Roca Partida. Activities:  4 dives Shark Behaviour Manta ID

Day 8

Voyage home.  Making our way back to Los Cabos. Activities:  Ship shop Trip slide show Cocktail with friends

Day 9

Disembarkation at 8:30AM. We recommend that you book your return flights for 10:00 AM or later.



As of Jan 2023, the Mexican government has suspended dive operations in Guadalupe indefinitely. The magical island of Guadalupe is 180 miles from the Mexico coastline. The coast of Guadalupe is 25 miles of rocky cliffs, but above this is dense forest, giving it the feel of an exotic, South Pacific destination. You can expect between 100 and 150 feet of visibility. We can literally see the sharks come in from beyond the anchor line. Nothing but clear, cobalt blue water.

Moreover, this experience isn’t limited to advanced divers. You don’t need to be a certified scuba diver to join us, although we recommend you take a Discover Scuba Diving course prior to your trip, and possess a strong in-water comfort.

All certified divers will have the opportunity for a minimum of three dives per day in the submersible cages—and your trip includes the opportunity for unlimited time in the surface cages. Divemasters are in the water during every submersible-cage dive to ensure your safety. Note that the surface cages open at 6:30 a.m., and diving in the submersible cages begins at 8 a.m. Both are available until dusk.

Our conservation efforts also continue at night when we kick back in the salon and identify who we spent the day with. And should you realize that you hung out with a great white shark not yet catalogued, yes, the naming rights are all yours.

Day 1
San Diego option: Meet at Best Western Palms Hospitality Suite and travel by coach to board the ship docked in Ensenada. Tijuana option: Fly into Tijuana and travel by express coach to Ensenada (90minutes).
Activities:  Evening departure from Ensenada

Day 2
Dinner time arrival at Guadalupe Island with a nice relaxing evening  at anchor.
Activities:  Safety Briefing  Diver Orientation  Shark 101 Cocktail hour at beautiful and peaceful anchorage

Day 3-5
Another full day of diving starting at 6:30 AM. Submersible diving starts at 8:30 AM.  Dive until dusk!
Activities:  Our famous Mexico taco Fiesta on the upper deck Shark ID​, cocktails with friends, theatre under the stars.

Day 6
At sea, arriving in Ensenada approx. 2:00 PM.  Coach transfers to Tijuana Airport, San Diego Airport, or Best Western Island Palms Resort. Activities: Trip Slide Show Our coach should arrive TIJ by 4:00 PM or San Diego by 7:00 PM if there are no  customs or weather delays.

Nautilus Conservation

Protecting Isla Guadalupe and Isla Socorro since 2005. Help our beloved sharks and mantas by contributing id images to the official databases for Guadalupe white sharks and Socorro giant mantas. Your contribution of good quality identification images are essential to monitoring and further study of these populations. You CAN make a difference!!

Nautilus enthusiastically support conservation, scientific research, film making and educational efforts around Guadalupe and Socorro Islands. In 2005 they founded the 501C3 registered Socorro Conservation Fund and 2 years later founded the 501C3 Guadalupe Conservation Fund. Are you interested in getting involved? Let us know when planning your trip.

What they’ve accomplished so far, with your help:

*Identified 170 (and counting!) individual sharks at Guadalupe Island with the help of Nicole Nasby, marine biologist.

*Raised over $300,000 between generous donations from our guests and financial support from Captain Mike for research, surveillance, tracking & equipment.

*Developed and implemented ID program using our boat’s satellite system. Photos are uploaded and shared with our researchers in real time.

7 -Night Trips Oct-Dec - from Cabo
Magdalena Bay rocks and we are pleased to announce the start of peak season trips during the best visibility and warmest water. And at precisely the best time of year for bait balls and snorkeling with striped marlin. 7 nights. Boarding in Cabo San Lucas on Oct 4, 2020. They thought the chances would be pretty remote of finding a new dive destination within a one day sail of Cabo San Lucas but that is indeed the latest news from Nautilus with 2 new wreck discoveries!

Magdalena Bay is at the confluence of a deep ocean upwelling as well as the California current and northerly current flowing up the pacific coast with some of the most biologically productive waters in the world. As Sten “the vikingo” so eloquently put it when he surfaced from one of his first dives on a July exploratory trip “there are a sh*t load of fish here”. Not to mention whales, dolphins, striped marlin, turtles, sea lions, schools with millions of sardines, and much more. Some people even starting to call this area the “Mexican sardine run”. Topping all this amazing diving is our discovery of surprisingly intact WWI submarine as well as the wreck of the steamship Independence in which 150 people perished.


Mantas, Sharks & Dolphin
Orcas & Mobulas & Whale Sharks on Sale
Aug 8-18, 2024 - half off
* cabins from $2900 (premium suite)