Tinian

• WWII munitions: The MVA warns explicitly that Dump Cove ordnance can remain live and phosphorus can ignite. Do not touch or collect artifacts, sift rubble, penetrate remains or attempt to recover anything.
• Overhead: Tinian Grotto contains an actual cavern; do not enter beyond an open-water environment without overhead training, equipment, qualified local guidance and an exit plan. This includes avoiding breath-hold penetration.
• Depth/boat conditions: Fleming's deep wall is not a proposed recreational depth. Plan with a certified guide; use a computer and surface-signaling gear. The Saipan crossing can be rough or canceled. Check NWS and listen to the captain.
• No-fly intervals: DAN recommends at least 12 hours after one no-stop dive and 18 hours after repetitive no-stop dives or multi-day diving, with longer intervals prudent for more complex profiles. A 15-minute Tinian-Saipan flight still constitutes flying. Symptoms of decompression illness mean no flight and urgent assessment.
• Medical readiness: Confirm oxygen kit, first-aid qualifications, marine communications and the operator's emergency plan before departure; the guide cannot certify any particular boat's equipment or active insurance.

Commonwealth Healthcare Corporation identifies the Lucia "Chiang" Villagomez Arizapa Health Center in San Jose as Tinian's only on-island medical facility, with a 24/7 emergency room and an inter-island medical referral program. Published contact numbers include +1 670 433-9233 and +1 670 433-9263. Its public page does not establish a currently operational hyperbaric chamber on Tinian, a guaranteed helicopter transfer or a fixed recompression destination. Do not invent these capabilities. For suspected decompression illness, activate emergency services (911), administer oxygen if trained and available, follow medical advice and coordinate with your dive operator and DAN emergency assistance, including +1 919 684 9111. Have evacuation-capable insurance verified before diving.

Treat the shore and reef as no-take in practice while verifying the law. The CNMI DLNR official MPA page characterizes the Tinian Marine Reserve as no-take, established by Public Laws 15-90 and 17-14, barring fishing, feeding fish, habitat damage and collection, with narrowly defined legal exceptions. Yet the DCRM 2025 public shore guide, page 10 states Tinian has no currently active MPA, while its Tachogna/Taga entries still call the waters a reserve. This is an unresolved official-source conflict, not a reason to relax conduct. Obtain current Division of Fish and Wildlife direction before fishing, collecting or other regulated uses. Do not stand on coral, feed fish, disturb turtles or remove shells, sand or wartime objects. Stay outside all restricted defense areas.