Siaes Tunnel - Rock Islands

Siaes Tunnel. Oh, Siaes Tunnel. This site often gets overlooked for its flashier neighbours, but for us, it’s one of the Rock Islands’ quiet heroes. You drop down, usually to about 15 metres, and then you’re pulling yourself along a line into the mouth of the tunnel itself. It’s not a cave, more like a massive swim-through, so there’s always an exit and plenty of ambient light filtering in. Inside, the atmosphere shifts. The water feels cooler, and the sound changes, a muffled quiet broken only by your own bubbles. We love to take our time here, letting our eyes adjust. The walls are covered in sponges and gorgonian fans, but it’s the fish life that really makes it special. We’ve seen huge schools of Pearl-jawed Cardinalfish hanging near the ceiling, their silver scales catching the light. Look closely on the sandy bottom for Prickly Redfish, sometimes a few Moorea Pygmygobies if you’re patient. Further in, the light turns a deep blue-green, and you might spot a few Pinktail Triggerfish darting around. It’s a drift out the other end, so you exit into the open ocean, often with a gentle current carrying you past vibrant reef walls. Perfect for divers who appreciate a more introspective, less adrenaline-fueled dive, and photographers who want to play with light and shadow.

Location
Rock Islands, Palau, Central & South Pacific
Coordinates
7.311444, 134.226620
Type
cave

Marine Protected Area: Ngerumekaol Spawning Area

Best Time to Dive in Rock Islands

The warmest water temperatures in Rock Islands occur in October, averaging 30.0°C. The coolest conditions are in February at 28.4°C.

Monthly Water Temperatures

  • January: 28.8°C
  • February: 28.4°C
  • March: 28.8°C
  • April: 29.3°C
  • May: 29.8°C
  • June: 29.9°C
  • July: 29.8°C
  • August: 29.7°C
  • September: 29.9°C
  • October: 30.0°C
  • November: 29.9°C
  • December: 29.6°C

Nearby Dive Sites in Rock Islands

Nearest Dive Centres to Siaes Tunnel

Marine Life in Rock Islands

Home to 198 recorded species including 171 reef fish, 15 sea cucumbers, 4 clams & mussels, 4 sea snails & nudibranchs, 2 starfish, 1 sea urchins.

Notable Species

Recommended Packing List for Siaes Tunnel

Based on average water temperature of 29.5°C, currents 13 cm/s.

  • Shorty or Rashguard - warm 30°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