Ot Di Ma

Ot Di Ma is a reef dive site in the central Dampier Strait of Raja Ampat — a local-language site name reflecting the indigenous Papuan geographic nomenclature of the archipelago, and a solid representative of the region’s extraordinary reef biodiversity.

Overview

Located in the Dampier Strait between Waigeo and the central islands, Ot Di Ma is a reef site that sees moderate use from liveaboards and local operators working the strait’s middle corridor. The reef presents a typical Dampier Strait profile: hard coral dominance in the shallows, a sloping structure down to 20–25 meters with increasing soft coral and sponge complexity, and the full complement of Indo-Pacific reef fish diversity that makes Raja Ampat the world’s most biodiverse marine environment. Water temperature averages 27–29°C and visibility is typically 12–20 meters.

Site Information

• Location: Raja Ampat, West Papua, Indonesia
• Entry Type: Boat dive
• Site Type: Reef
• Difficulty Level: Intermediate
• Maximum Depth: 25 meters
• Typical Visibility: 12–20 meters (40–65 feet)
• Current: Variable; moderate on tidal exchange
• Best Time: October to April

Marine Life

Ot Di Ma’s central Dampier Strait position means it benefits from the tidal exchange that feeds Raja Ampat’s reef productivity. Schooling fusiliers and snapper fill the mid-water zone. Napoleon wrasse, hawksbill turtles, and large groupers are resident. White-tip reef sharks rest at the reef base. The coral gardens in the upper reef support dense populations of butterflyfish, angelfish, and parrotfish. Nudibranch diversity on the substrate between coral heads is excellent — Raja Ampat’s nudibranch species count is among the highest in the world.

Dive Profile

Begin at the reef crest in the shallows and follow the slope down to 20–25 meters. Spend time at each depth band, noting the transition from hard to soft coral as depth increases. The lower reef base is productive for resting sharks and larger fish. Ascending slowly, pause at 12–15 meters to enjoy the schooling fish and resident reef fish activity. Finish with a comfortable safety stop in the coral shallows.

Entry and Exit

Boat access from Dampier Strait operators or liveaboards. Entry via giant stride. The central strait location means some current management may be required. Deploy SMB on ascent — the Dampier Strait has significant boat traffic.

Tips and Recommendations

• A torch helps with crevice inspection throughout the dive
• Look carefully at rubble sections between coral heads for ghost pipefish and leaf scorpionfish
• Ask your guide about recent sightings at this specific site
• Pair with adjacent strait sites for efficient multi-dive day coverage

Safety Considerations

Standard intermediate reef protocols. Moderate currents possible during tidal exchange. Carry an SMB. The Dampier Strait sees heavy liveaboard traffic — surface visibility and SMB deployment are important.

Photography

Good all-round reef photography. Hard coral gardens in the shallows, schooling fish in mid-water, soft coral at depth, and macro on the substrate provide diverse subjects in a single dive. Natural light quality is good in the upper 15 meters during morning dives.

Sources: Papua Diving - Raja Ampat Dive Sites, Bluewater Dive Travel - Raja Ampat Diving, La Galigo Liveaboard - Top 10 Raja Ampat Dive Sites, Girls That Scuba - Scuba Diving Raja Ampat, PADI - Diving in Raja Ampat. Last updated 2026-04-04.