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Grand Cayman Bio Bay in October 2027: darkest nights

Boat tours leave from Rum Point and Kaibo. Operators cancel on bright full-moon nights. Year-round.

16 pitch-dark nights, 18 dark nights

New moon Fri 29 Oct · Full moon Fri 15 Oct

Night by night, October 2027

NightMoon19:0020:30Best
Fri 1 Oct 6%●●●●●●●●●●20:30
Sat 2 Oct 12%●●●●●●●●●●20:30
Sun 3 Oct 19%●●●●●●●●●●20:30
Mon 4 Oct 28%●●●●●●●●●●20:30
Tue 5 Oct 37%●●●●●●●●●●20:30
Wed 6 Oct 47%●●●●●●●●●●20:30
Thu 7 Oct 56%●●●●●●●●●●20:30
Fri 8 Oct 66%●●●●●●●●●●20:30
Sat 9 Oct 74%●●●●●●●●●●20:30
Sun 10 Oct 82%●●●●●●●●●●20:30
Mon 11 Oct 89%●●●●●●●●●●20:30
Tue 12 Oct 94%●●●●●●●●●●20:30
Wed 13 Oct 98%●●●●●●●●●●19:00
Thu 14 Oct 100%●●●●●●●●●●19:00
Fri 15 Oct 100%●●●●●●●●●●19:00
Sat 16 Oct 97%●●●●●●●●●●19:00
Sun 17 Oct 93%●●●●●●●●●●19:00
Mon 18 Oct 86%●●●●●●●●●●19:00
Tue 19 Oct 78%●●●●●●●●●●19:00
Wed 20 Oct 67%●●●●●●●●●●20:30
Thu 21 Oct 56%●●●●●●●●●●20:30
Fri 22 Oct 44%●●●●●●●●●●20:30
Sat 23 Oct 33%●●●●●●●●●●20:30
Sun 24 Oct 22%●●●●●●●●●●20:30
Mon 25 Oct 13%●●●●●●●●●●20:30
Tue 26 Oct 7%●●●●●●●●●●20:30
Wed 27 Oct 2%●●●●●●●●●●20:30
Thu 28 Oct 0%●●●●●●●●●●20:30
Fri 29 Oct 1%●●●●●●●●●●20:30
Sat 30 Oct 4%●●●●●●●●●●20:30
Sun 31 Oct 8%●●●●●●●●●●20:30

Check one night in detail Grand Cayman Bio Bay tours

Questions

What are the best nights to see the bioluminescence at Grand Cayman Bio Bay in October 2027?

The darkest nights are Fri 1 Oct, Sat 2 Oct, Sun 3 Oct, Tue 19 Oct, Wed 20 Oct, Thu 21 Oct, Fri 22 Oct, Sat 23 Oct, Sun 24 Oct, Mon 25 Oct and more. 18 of 31 nights score at least 4 out of 5.

Which nights should I avoid in October 2027?

Avoid the nights around the full moon on Fri 15 Oct, when moonlight washes out the glow.

19:00 or 20:30: which Grand Cayman Bio Bay tour is darker in October?

19:00 is the darker choice on 2 nights; 20:30 is the darker choice on 17 nights.

Grand Cayman Bio Bay darkness by month

Darkness score 1-5 per tour slot from twilight and moonlight. Weather and plankton health are not included. Times are local (America/Cayman).