Dive Site: Arco Iris

About Arco Iris

Arco Iris, or "Rainbow" in Spanish, is a prominent dive site located near Brumel Island (Penahuaste), approximately 8km north of Playa Potrero in Costa Rica. Easily accessible by a short boat ride, this site is characterized by a distinctive rock formation that extends northward from the island's northwest face, creating a diverse underwater landscape. The topography transitions from a rock face to wide sandy channels, with depths ranging from 9 to 30 meters. These channels are often teeming with schools of grunts, and offer opportunities to find multiple white-tip reef sharks resting or cruising. The deepest sandy patches can reach around 24 meters. The site is consistently active with marine life, including frequent sightings of white-tip reef sharks, various ray species, and large schools of fish. Nurse sharks, moray eels, and octopus are also commonly encountered. While specific seasonality for these creatures is not detailed, the vibrant ecosystem provides exciting encounters year-round. With its relatively shallow average depth of 9 meters and a maximum of 30 meters, Arco Iris is suitable for divers across all experience levels. A knowledgeable local guide is highly recommended to help divers locate the numerous sharks and fully appreciate the site's highlights.

Dive site facts: Arco Iris

Depth

9–30 m

Typical dive

9–19 m, 50–60 min (estimated)

Current

Variable

Visibility

Very good

Water temperature

18–27°C (65–80°F)

Entry

Boat / back-roll

Level

All levels

Dive type

Reef, big animals, shark

Region / port

Guanacaste, Playa Potrero

Coordinates

7.8574° N, 86.1272° W

Conditions & Currents

Currents at Arco Iris are variable, influenced by open sea movements, particularly in the sandy channels. While typically manageable for most divers, current strength can fluctuate, especially near deeper sections where grunts often swirl. Divers should be prepared for potential drift and maintain good buoyancy control, especially when navigating the interconnected sandy channels. Entry is typically a standard boat entry, and a local guide will assess conditions to ensure a safe and enjoyable dive, including consideration for exit techniques.

Marine life & sighting chances

White-tip reef shark

common

Ray

common

Nurse shark

occasional

Eagle ray

occasional

Round ray

occasional

Moray eel

common

Octopus

occasional

Grunts

common

Lobster

occasional

Fish schools

common

Sea turtle

occasional

Seahorse

rare

Dive profile & how the dive runs

Diving at Arco Iris typically begins with a boat entry onto the reef near the distinct rock formation. The dive plan often involves following the rock face from an initial depth of around 12-15 meters. Divers then proceed to a wide sandy channel, where conditions permitting, they can explore for schools of grunts. Turning to follow the rock formations on the left, the route leads to several interlinking sandy channels, renowned for sightings of numerous white-tip reef sharks resting. While the deepest sandy patch reaches about 24 meters, divers can maintain shallower depths along the rocks, looking for rays and turtles. The dive concludes by circling back along the main rock face for a safety stop before surfacing for boat pickup.

Underwater photography

Arco Iris offers excellent opportunities for underwater photography, particularly for wide-angle shots due to the large rock formations, numerous sharks, and schooling fish. With depths ranging from 9 to 30 meters, ambient light is generally good in shallower areas, making it suitable for capturing the overall grandeur of the site. A wide-angle lens is ideal for showcasing the impressive topography and the dense schools of grunts and white-tip reef sharks. For close-up encounters with rays, moray eels, or octopus, a macro lens can be rewarding, especially in the sandy channels. Good buoyancy control is essential to avoid stirring up sediment and to approach marine life respectfully for clear, impactful images.

Combine with nearby dive sites

• Brumel Shallow

  A sheltered, beginner-friendly site from Flamingo Bay, offering calmer conditions.

• Brumel Deep

  A deeper, also sheltered site suitable for various skill levels near Flamingo Marina.

• Escorpiones

  A shallow ledge with rocky formations and sandy areas, home to small critters and larger marine life.

• Cuatro Piedras

  An excellent site for beginners with a shallow sandy patch, though currents can be challenging.

• Los Sombreros

  A volcanic island site with sombrero-shaped rock formations, known for sharks and rays.

• Bajo Negro

  A site known for surprising pelagic encounters and strong currents near Bat Island.

Getting there & logistics

Arco Iris is typically accessed by boat, with travel times often less than 20 minutes from coastal towns like Playa Potrero. Dive operators in the Guanacaste region, including those from Playas del Coco, offer day trips to this site. Most trips are half-day excursions, often combining two dives at Arco Iris or one at Arco Iris with another nearby site like Brumel Shallow or Escorpiones. Costa Rica's main international airport, Daniel Oduber Quirós International Airport (LIR) in Liberia, is the closest gateway to the Guanacaste region. No specific permits or fees are mentioned for diving Arco Iris itself, but general dive trip costs include boat travel and guide services.

Safety & environment

While Arco Iris is considered suitable for all levels, divers should be aware of variable currents that can occur, particularly when navigating the sandy channels. Maintaining good buoyancy control and staying close to the dive guide are crucial, especially when currents are stronger. The nearest recompression chamber or advanced medical facilities are likely in larger cities or regional hospitals in the Guanacaste province, requiring boat transfer and potentially a significant drive. Dive insurance covering emergency evacuation and hyperbaric treatment is strongly recommended for all divers visiting Costa Rica. Always dive with a reputable operator and ensure your equipment is well-maintained.

Who it suits — and who it doesn't

FAQ

Arco Iris FAQ

Liveaboards diving Arco Iris

These liveaboards may visit Arco Iris on selected itineraries — the exact dive sites depend on departure, weather and conditions.

Cocos Aggressor

Costa Rica

22 guests37.8 m

$477/day

Sea Hunter

Costa Rica

20 guests

$690/day

Okeanos Aggressor II

Costa Rica

24 guests36.6 m

$582/day