Short adventure: The Trident of Malik-Norrn

Bterek the Unholy, exiled priest of Ghan, is a frequent sight amidst the worst of the wharf-side alehouses of the PC's current base-town. Driven to alcholism by the stripping away of his clerical powers by a jealous rival with higher favor from Ghan, Bterek has taken to selling various anitiquities, charms, legends, and treasure maps to support his daily drunk. Where he comes up with these items and lore is anyone's guess. Most of the time they are useless junk, false leads, or outright traps, but every so often (say, 1 in 10), he comes up with something useful, such as his current item for sale: a map leading the Sunken Coral Shrine of Malik-Norrn, fabled resting place of the legendary Trident of Malik-Norrn.

The map leads to a deserted stretch of beach some miles south of town. On moonlit nights, the tide lowers enough to reveal the Sunken Coral Shrine, a large Stonehenge--like monument of pink and white coral, five concentric rings of pillars deep. While the sea-floor around the outermost ring is completely free of water, each succesive ring gets progressively deeper, until it becomes chest-deep within the inner-most ring. Here, the Trident is set into a slot in a massive block of coral in the very center.

Within the outer rings lurk from 3-12 giant crabs at any time, who like to bask in the dark aquatic energies radiating from the trident. They are immediately hostile to interlopers.
Giant Crabs(3-12): HD 3; AC 3[16]; Atk 2 pincers (1d6+2); Move 9; Save 14; CL/XP 3/60; Special: None.

Guarding the innermost ring and the Trident itself is Bflefguul, a Chaotic water naga. Bflefguul will remain hidden while the crabs fight interlopers, revealing himself only if the innermost ring is reached. He is saturnine, cruel, and clever. If he feels outmatched, he will attempt to delay the party with gibes, riddles, and double-talk, as 1d3 crabs per turn will arrive at the area due to the Trident's influence. When the crabs arrive, Bflefguul will assist the crabs with spells.
Water Naga: HD 7; AC 5[14]; Atk 1 bite (1d4 + poison); Move 12 (Swim 20); Save 9; CL/XP 10/1400; Special: Poison, spells: Charm Person, Magic Missile x2, Sleep; level 2: Mirror Image, Stinking Cloud; level 3: Suggestion

If Bflefguul is defeated, the PCs are free to lay claim to the Trident of Malik-Norrn!

Trident of Malik-Nornn: This +2 Trident is +3 versus aquatic creatures. Once per day, it enables its wielder to use the spells Stinking Cloud, Water Breathing, and Darkvision.