Senanus Island - Pacific Northwest

Senanus Island is one of those spots in the Pacific Northwest that consistently delivers, even when the mainland sites are a bit surly. We love it because you’re almost guaranteed to see something interesting, even if it’s just the sheer density of life clinging to the walls. Drop in, and you’re immediately enveloped in a kaleidoscope of colour from the star ascidians – patches of bright orange and purple, almost glowing against the often-dark rock. Keep your eyes peeled for those prickly sculpins, masters of camouflage, and the slender crabs scuttling amongst the anemones. We’ve had some fantastic encounters with schools of coho salmon here, especially when they’re moving through the channels, a flash of silver against the green water. The real treat for us, though, is poking around the cracks and crevices for California spot prawns and the less common four-spined squat lobsters. Our favourite time to dive here is on a slack tide, just after the morning rush, when the visibility tends to be at its best and the currents are a bit more forgiving. If you’re into macro life and don’t mind a bit of a chill, Senanus is a solid bet for a memorable dive.

Location
Pacific Northwest, United States, North America
Coordinates
48.591930, -123.486020
Type
reef
Maximum Depth
10-30m

Marine Protected Area: Kellett Bluff Voluntary No-take

Best Time to Dive in Pacific Northwest

The warmest water temperatures in Pacific Northwest occur in August, averaging 16.5°C (up to 15.6°C). The coolest conditions are in February at 6.9°C.

Monthly Water Temperatures

  • January: 7.1°C (air: 6.3°C)
  • February: 6.9°C (air: 4.5°C)
  • March: 7.7°C (air: 6.6°C)
  • April: 9.5°C (air: 8.7°C)
  • May: 12.0°C (air: 11.7°C)
  • June: 14.0°C (air: 13.7°C)
  • July: 15.7°C (air: 14.9°C)
  • August: 16.5°C (air: 15.7°C)
  • September: 14.3°C (air: 14.0°C)
  • October: 11.4°C (air: 10.5°C)
  • November: 8.8°C (air: 7.4°C)
  • December: 7.7°C (air: 5.5°C)

Nearby Dive Sites in Pacific Northwest

Nearest Dive Centres to Senanus Island

Marine Life in Pacific Northwest

Home to 38 recorded species including 18 reef fish, 7 crabs & lobsters, 3 whales & dolphins, 2 sharks & rays, 2 clams & mussels, 2 sea urchins.

Notable Species

Recommended Packing List for Senanus Island

Based on average water temperature of 11.0°C, currents 7 cm/s.

  • Wetsuit (5-7mm) - recommended for 11°C water
  • Hood & Gloves (3-5mm) - helps retain warmth
  • 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