UNISON IV - Southern Islands

The UNISON IV is our favourite local wreck, not because it’s a giant, but because it’s so… *there*. Sunk in 1990, this 70-meter motor vessel sits upright and largely intact, making for an incredibly atmospheric dive. We love dropping down onto the main deck, often with schooling fusiliers swirling above us like a silver curtain. You can still make out the superstructure, the bridge, even the mast reaching towards the surface – it's a proper ship shape. What really makes the UNISON IV shine is the life that’s colonised it. Every crevice seems to hold something. Look for batfish hovering lazily around the mast, and we’ve often found lionfish tucked into doorways. On a sunny day, the light filters through the upper sections, creating these fantastic shafts of light, almost theatrical. It’s a site that rewards multiple dives; you always spot something new, a different angle, another resident moray eel peeking from a porthole. It’s perfect for divers who appreciate history and the way the sea reclaims its own, offering plenty to explore without being overly challenging.

Location: Southern Islands, Singapore, Southeast Asia
Coordinates: 1.278194, 103.740840
Type: wreck
Maximum Depth: 15m

Marine Protected Area: Labrador Nature Reserve

Best Time to Dive in Southern Islands

The warmest water temperatures in Southern Islands occur in January, averaging 28.2°C. The coolest conditions are in December at 28.2°C.

Monthly Water Temperatures

January: 28.2°C (air: 26.0°C)
February: 28.2°C (air: 26.6°C)
March: 28.2°C (air: 27.1°C)
April: 28.2°C (air: 27.4°C)
May: 28.2°C (air: 27.9°C)
June: 28.2°C (air: 27.4°C)
July: 28.2°C (air: 27.5°C)
August: 28.2°C (air: 27.2°C)
September: 28.2°C (air: 27.2°C)
October: 28.2°C (air: 27.2°C)
November: 28.2°C (air: 26.5°C)
December: 28.2°C (air: 26.3°C)

Nearest Dive Centres to UNISON IV

Marine Life in Southern Islands

Home to 284 recorded species including 179 reef fish, 46 hard corals, 17 seagrass & algae, 13 sharks & rays, 8 sea snails & nudibranchs, 6 other.

Notable Species

Species code: Ea (Enhalus acoroides) - Seagrass & Algae
thalassia (Thalassia hemprichii) - Seagrass & Algae
seagrass (Halophila ovalis) - Seagrass & Algae
halodule (Halodule uninervis) - Seagrass & Algae
cymodocea (Cymodocea rotundata) - Seagrass & Algae
Species code: Si (Syringodium isoetifolium) - Seagrass & Algae
Brain coral (Platygyra sinensis) - Hard Corals
Staghorn coral (Acropora millepora) - Hard Corals
Staghorn coral (Acropora hyacinthus) - Hard Corals
Fluorescence grass coral (Galaxea fascicularis) - Hard Corals
Staghorn coral (Acropora valida) - Hard Corals
Honeycomb coral (Favites abdita) - Hard Corals
Galaxea coral (Galaxea astreata) - Hard Corals
Species code: Tc (Thalassodendron ciliatum) - Seagrass & Algae
Bristle-tailed Leatherjacket (Acreichthys tomentosus) - Reef Fish
Green Turtle (Chelonia mydas)
Butterfish (Scatophagus argus) - Reef Fish
Stony coral (Echinopora lamellosa) - Hard Corals
Staghorn coral (Acropora nasuta) - Hard Corals
Savigny's Brittle Star (Ophiactis savignyi)

Recommended Packing List for UNISON IV

Based on average water temperature of 28.2°C.

Shorty or Rashguard - warm 28°C water needs minimal exposure protection
Mask - essential for every dive
Fins
BCD - buoyancy compensator
Regulator - your most safety-critical piece of gear
Dive Computer - tracks depth, time, and NDL
Surface Marker Buoy (SMB) - essential for boat pickups
Dive Torch - useful for crevices and colour at depth
Underwater Camera - capture your diving memories