a sandbar serpent

• -1112, 301, 64 (seen once)
• 620, 18, 73 (seen once) (1 of 2 spawns here)
• -364, -1203, -9 (seen once)
• -606, -1011, -8 (seen once)
• 922, -719, 109 (seen once)
• -309, -37, -144 (seen once)
• 155, -1433, -231 (seen once)
• -1657, -171, 165 (seen once)
• 740, 260, 52 (seen once)
• -17, -1741, -65 (seen once)
• -94, -843, 90 (seen once)
• -982, -1036, -11 (seen once)
• -553, -1114, 6 (seen once)
• -927, -1250, -289 (seen once)
• -1605, -342, 111 (seen once) (1 of 3 spawns here)
• 652, 167, 8 (seen once)
• -1130, -942, -87 (seen once)
• -932, -1689, -49 (seen once)
• -533, -77, -8 (seen once)
• -783, 135, -8 (seen once)
• 965, -711, 122 (seen once)
• -1000, 465, 98 (seen once) (1 of 2 spawns here)
• 240, -1834, -173 (seen once)
• 953, -822, 138 (seen once) (1 of 4 spawns here)
• -1314, -70, -55 (seen once)
• -1089, -1395, -8 (seen once)
• -321, 503, 137 (seen once)
• -157, -241, -96 (seen once)
• -387, 531, 156 (seen once)
• -1261, -170, -68 (seen once) (1 of 2 spawns here)

As /loc gives them: Y, X, Z, the most used first; nearby spawns share a spot, and one seen in a single visit may be where the mob had been pulled to.