Isthmus
Also known as: The Isthmus
Dive siteFrom Puerto Rico Dive Sites, the sourced field guide
Isthmus
| Region | Isla de Mona & Monito |
|---|---|
| Municipality | Mayagüez |
| Island | Isla de Mona |
| Access | Access not established |
| Site type | Wall |
| Depth (reported range) | Unknown |
| Protected area | Isla de Mona Natural Reserve |
| Location | No reliable coordinates yet. |
| Confidence | Moderate confidence |
| Last researched | 2026-10-17 |
Overview
The Isthmus is a wall dive off Isla de Mona that training-agency blogs describe as sheer, dramatic vertical walls with gorgonian sea fans and black coral in the current. One blog rates it for experienced divers. Published depth information is lacking. It is reported to lie within Isla de Mona Natural Reserve, which NOAA lists as having no-take zones, with fishing and anchoring restricted; check current DRNA rules.[1][2][3]
Site characteristics
Habitat & marine life
- gorgonian sea fans and black coral in current[1]
Marine life is what sources report having seen or commonly seeing — not a guarantee.
Experience & conditions
- SSI (Scuba Schools International): “SSI blog: for experienced divers”[1]
Attributed descriptions from sources, not our rating. Conditions vary; your training, experience and the day’s conditions decide.
Recent diver reports
Dived here recently? Share a quick report
First-hand reports from divers, reviewed before they appear. Conditions change daily; a report describes one day.
Safety considerations
No site-specific hazards are recorded in our sources. That does not mean there are none.
Ocean conditions change daily. Dive within your training, plan with current local information and consider a local professional guide. Water safety guide.
Protected area
Isla de Mona Natural Reserve (Reserva Natural Isla de Mona)
Natural Reserve · Puerto Rico Department of Natural and Environmental Resources · Reported by a source as within this area[3]
NOAA's MPA Inventory classifies this area's protection level as "Zoned w/No Take Areas"; fishing: commercial and recreational fishing restricted. Anchoring: restricted.[3]
Regulations change. Check with DRNA (Departamento de Recursos Naturales y Ambientales) before diving.
Sources & verification
Last researched: 2026-10-17 · Last independently verified: not yet field-verified · Confidence: Moderate confidence
- 1.Discovering Paradise: The Ultimate Guide to Scuba Diving in Puerto Rico — SSI (Scuba Schools International) · Dive organization · Tier 3: Corroborating · accessed 2026-09-25
- 2.Best Dive Sites in Puerto Rico — PADI / Scuba Diving (2026-02-11) · Dive organization · Tier 3: Corroborating · accessed 2026-10-11
- 3.NOAA Marine Protected Areas Inventory 2024 (feature service NOAA_MPA_Inventory_2023), State = PR — NOAA NOS Office of National Marine Sanctuaries - MPA Center (2024) · Government dataset · Tier 1: Primary / authoritative · accessed 2026-09-25
Facts are summarised in our own words from the sources above; we do not reproduce operators’ or publishers’ descriptions. How confidence is assigned.