• A Seamount Built for Pelagics: Rising from the abyss, Castle Rock draws schooling jacks and giant trevally, white-tip and occasional silky sharks, and epaulette sharks resting on the reef. Divers have also reported passing Mola mola (sunfish) here. • A Cavern and Overhang: Near 28 meters, the rock hides a cavern and overhang system home to humphead wrasse, scorpionfish, pipefish, and zebra moray — a striking contrast to the open-water action above. • A Genuine Drift Dive: Castle Rock's current is consistently one of the stronger drifts in the park, capable of carrying divers a considerable distance in a single dive — which is exactly what pulls in the pelagic traffic. • Steep Drop-Offs: The topography is dramatic, with the wall dropping through roughly 15–40 meters, occasional night currents, and little in the way of a gentle slope.

• Drift Diving the Wall: This is Castle Rock's signature experience — descending onto the seamount and letting the current carry you along the wall while schools of trevally and jacks stream past. • Exploring the Cavern: On a receding tide, the cavern near 28 meters opens up fully, rewarding divers who linger with a wide-beam torch for the smaller reef life hiding inside. • Timing the Tide: Guides generally favor either an afternoon window, when the wind settles into a steady, predictable drift, or a receding tide that best exposes the cavern — ask your dive master which approach the day's conditions favor. • Pairing with Nearby Sites: Castle Rock is frequently dived on the same day as Crystal Rock or Batu Bolong, making a natural two- or three-site day for a dedicated dive charter.

The dry season (April–October) brings the steadiest conditions for reading the current correctly. Within a given day, afternoon dives (roughly early-to-mid afternoon) often catch the wind-driven drift at its most predictable, while a receding tide is preferred for divers aiming to explore the cavern. Either way, Castle Rock rewards divers who dive it with a guide who tracks the local tide charts closely.

Castle Rock lies east of Komodo Island, reached by boat from Labuan Bajo — generally a stop on a multi-day Phinisi liveaboard rather than a short day trip, since it's often paired with other northern dive sites like Crystal Rock on the return leg toward Labuan Bajo. Dedicated dive charters build entire itineraries around Castle Rock and Batu Bolong together.

• Advanced Certification Only: This is not a beginner site — an Advanced Open Water certification, ideally with Drift or Deep training, is the realistic minimum. • Brief Before You Descend: Strong, sometimes shifting currents mean a thorough pre-dive briefing on entry points, hand signals, and emergency ascent procedures matters more here than at gentler sites. • Carry a Surface Marker Buoy: In a genuine drift dive, an SMB helps your boat track you if the current pushes you off the planned line. • Never Dive Alone: Buddy discipline is essential — the current can separate divers quickly. • Respect the Cavern's Residents: Zebra morays, scorpionfish, and pipefish are easily disturbed; keep your fins and hands well clear of the overhangs.

Castle Rock is one of the sites that gives Komodo its reputation as an advanced-diver destination rather than a beginner's playground. It sits alongside Batu Bolong as one of the two sites most commonly cited when operators explain Komodo's certification requirements — both call for an Advanced Open Water certification, with a Drift or Deep specialty strongly recommended given the strength and consistency of the current here.