Mariana Islands – Guam & Saipan

The southern Mariana Islands split into US-territory Guam and the Commonwealth of the Northern Mariana Islands (Saipan, Tinian, Rota). Guam is known for the twin wrecks of the German WWI raider SMS Cormoran and the Japanese freighter Tokai Maru in Apra Harbor, the Blue Hole off Orote Point and a string of outer-reef walls. Saipan adds the Grotto cavern, drop-offs such as Naftan Point and the protected WWII Maritime Heritage Trail of aircraft, landing craft and ships in its lagoon. Tinian and Rota are reached by short boat trips or small planes and offer clear water, caverns such as Rota Hole and the Shoun Maru wreck.

Facts

Best season: Year-round; the calm season is roughly May–September on the northern Saipan sites (Banzai, Wing Beach, Spotlight), which are only diveable then
Water temperature: About 28–30 °C (82–86 °F) year-round per the Guam Visitors Bureau
Visibility: Outer reef and walls often 30 m or more; Apra Harbor wrecks 8–12 m
Getting there: Fly to Guam (GUM) or Saipan (SPN); Tinian is a boat trip from Saipan (about 50 min), Rota is reached by small plane or ferry-type service
Protected areas: Guam: Piti Bomb Holes and Tumon Bay marine preserves (no fishing, rules from the Guam Department of Agriculture, DAWR). CNMI: Managaha Marine Conservation Area and the Saipan Maritime Heritage Trail; Rota: Sasanhaya Bay Fish Reserve protecting the Shoun Maru and sub chaser
Currents: Mostly mild inside the lagoons and harbor; strong at exposed points (Banzai Cliff, Naftan Point, Rota walls, Grotto surge) - carry a surface marker

Season

Best months: Jan, Feb, Mar, Apr, May, Jun
Acceptable: Jul, Aug, Dec
Poor: Sep, Oct, Nov
Water temperature: 27–30 °C

Dry season roughly Dec–Jun gives the best visibility; typhoon season Jul–Nov (peak late Aug to mid-Nov on Guam). Most Guam sites are on the sheltered west side and can be dived year-round.

Dive sites (32)

Guam

American Tanker – 13–27 m, intermediate
Blue Hole (Guam) – 12–38 m, advanced
Fish Eye / Piti Bomb Holes – 5–11 m, beginner
Gab Gab II – 11–21 m, beginner
Hap's Reef – 14 m, beginner
Kitsugawa Maru – 18–43 m, advanced
Shark's Pit – 5–32 m, intermediate
SMS Cormoran – 24–37 m, advanced
The Crevice – advanced
Tokai Maru – 13–37 m, advanced

Saipan

Banzai Cliff – 15–40 m, advanced
Dimple – 12–40 m, beginner
Emily Flying Boat (H8K) – 8–10 m, beginner
Ice Cream – 5–16 m, beginner
Japanese Landing Craft (Daihatsu) – 10–12 m, beginner
Lau Lau Beach – 0–20 m, beginner
Naftan Point – 14–60 m, intermediate
Obyan Beach – 5–18 m, beginner
Sherman Tanks (Susupe / Chalan Kanoa) – 1–3 m, beginner
Shoan Maru (Chinsen Maru) – 8–11 m, beginner
The Grotto – 0–30 m, intermediate
Wing Beach – 30 m, advanced

Rota

Coral Garden – 25 m, beginner
Rota Hole – 18 m, advanced
Senhanom Drop Off – 35 m, intermediate
Shoun Maru – 33 m, intermediate
Sub Chaser – 28 m, beginner
Table Top – 30 m, beginner

Tinian

Dump Cove – 20 m, intermediate
Fleming – 10–33 m, intermediate
Tinian Grotto – 0–25 m, intermediate
Two Coral Heads – 16 m, beginner

Operators (6)

Masa Dive Saipan – dive centre, Garapan, Saipan
Aqua Connections Saipan – dive centre, Saipan
Let's Go Diving Saipan – dive centre, Saipan
Rota Dive Service Blue Palms – dive centre, Rota
Go Dive Guam – dive centre, Tamuning, Guam
Micronesian Divers Association (MDA) – dive centre, Piti, Guam

Routes (4)

Site positions are approximate unless marked otherwise and are for orientation only - never for navigation. WWII wrecks hold unexploded ordnance and are protected heritage sites: do not touch, and take no souvenirs. Wreck penetration needs proper training; always dive with a local guide.