Diver's Almanac
Gulf of Thailand Tides & Moon Calendar 2025
Full-year moon phases and tidal-strength calendar for the Gulf of Thailand. Yellow-highlighted days = spring tides (larger tidal range, stronger currents, especially at shallow sites). White days = neap tides (smaller range, calmer currents).
January
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
6
◐
7
◐
8
9
10
11
12
13
14
○
15
16
17
18
19
20
21
◑
22
◑
23
24
25
26
27
28
●
29
●
30
31
February
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
◐
6
7
8
9
10
11
12
○
13
○
14
15
16
17
18
19
◑
20
◑
21
22
23
24
25
26
27
●
28
●
March
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
6
◐
7
◐
8
9
10
11
12
13
14
○
15
16
17
18
19
20
21
◑
22
◑
23
24
25
26
27
28
●
29
●
30
31
April
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
◐
6
◐
7
8
9
10
11
12
○
13
○
14
15
16
17
18
19
20
◑
21
22
23
24
25
26
27
●
28
●
29
30
May
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
◐
5
◐
6
7
8
9
10
11
12
○
13
14
15
16
17
18
19
◑
20
◑
21
22
23
24
25
26
●
27
●
28
29
30
31
June
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
◐
4
◐
5
6
7
8
9
10
○
11
○
12
13
14
15
16
17
18
◑
19
20
21
22
23
24
25
●
26
●
27
28
29
30
July
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
◐
3
◐
4
5
6
7
8
9
10
○
11
12
13
14
15
16
17
◑
18
◑
19
20
21
22
23
24
●
25
●
26
27
28
29
30
31
August
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
◐
2
◐
3
4
5
6
7
8
○
9
○
10
11
12
13
14
15
16
◑
17
18
19
20
21
22
23
●
24
●
25
26
27
28
29
30
◐
31
◐
September
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
6
7
○
8
○
9
10
11
12
13
14
◑
15
◑
16
17
18
19
20
21
22
●
23
24
25
26
27
28
29
◐
30
◐
October
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
6
○
7
○
8
9
10
11
12
13
14
◑
15
16
17
18
19
20
21
●
22
●
23
24
25
26
27
28
◐
29
◐
30
31
November
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
5
○
6
○
7
8
9
10
11
12
◑
13
◑
14
15
16
17
18
19
20
●
21
22
23
24
25
26
27
◐
28
◐
29
30
December
Sun
Mon
Tue
Wed
Thu
Fri
Sat
1
2
3
4
○
5
○
6
7
8
9
10
11
12
◑
13
◑
14
15
16
17
18
19
●
20
●
21
22
23
24
25
26
27
◐
28
29
30
31
Reading the calendar
- ● New moon — peak spring tide, stronger currents
- ○ Full moon — peak spring tide, stronger currents
- ◐ / ◑ First / last quarter — neap tide, weakest currents
- Spring-tide days (70%+ intensity)
- Moderate spring-tide days (40-70%)
What this means for diving
Spring tides near new and full moon create larger tidal ranges. In the Gulf of Thailand (small-tide sea) this means:
- Stronger tidal currents at shallow coastal sites (under 20m)
- More water movement near reefs — sometimes better for encountering pelagic fish
- Stirred-up sediment at some sites — reduced visibility
Neap tides (quarter moons) give calmer water, usually better visibility at coastal sites, and easier conditions for beginners.
Deep pinnacles like Sail Rock and Chumphon are less affected by tides — weather and ocean currents matter more there.