Japanese Cave (Abyab Binsari)

Origin and Naming of Abyab Binsari

Before the arrival of Japanese soldiers, this cave was known by the local Biak people as "Abyab Binsari". In the local language, Abyab means cave, while Binsari refers to an "old grandmother". According to the legend of the Ambai Village community, an old grandmother once lived inside the cave. However, after the Japanese soldiers entered and occupied the Biak region in 1942, the grandmother's presence mysteriously disappeared, and the cave's function completely changed from a natural shelter to a strategic military base.

Architectural Characteristics and Space Utilization

Gua Jepang (Abyab Binsari) is a very large karst (limestone) cave. Architecturally, it has a multi-level structure with interconnected passages. The total length of these cave passages is estimated to be several kilometers, reportedly extending to the Parai coast.

During the Japanese occupation (1942–1944), Japanese soldiers made extensive modifications to the cave's interior without drastically altering the natural rock structure. They built partitions from wood and concrete to create functional spaces, including:

1. Command Center: A large room used by high-ranking officers to plan war strategies.

2. Soldier Barracks: Passages capable of housing up to 3,000 soldiers at once.

3. Logistics Warehouse: Storage for ammunition, weapons, and food supplies.

4. Emergency Hospital: A dedicated space for treating soldiers wounded in battles around Mokmer Airport (now Frans Kaisiepo Airport).

The uniqueness of this cave lies in its natural ventilation holes at the top, which provided lighting and air circulation, making it an ideal and hard-to-detect defensive fortress for Allied aerial reconnaissance at that time.

Historical Significance: The Battle of Biak 1944

Gua Abyab Binsari played a crucial role in the "Battle of Biak" that erupted from May to June 1944. Biak was considered strategic by General Douglas MacArthur due to the presence of three airstrips built by the Japanese. For Japan, defending Biak meant hindering the Allied advance towards the Philippines and Japan.

Under the command of Colonel Naoyuki Kuzume, Japanese soldiers employed a "deep defense" tactic. Instead of confronting the Allies on the beaches, they allowed US forces to land and then trapped them in a guerrilla war from within the karst caves, including Abyab Binsari. This strategy initially overwhelmed the US 41st Division due to the Japanese positions protected underground.

Tragic Event of Annihilation

The peak of the cave's dark history occurred on June 21, 1944. Realizing that a direct assault through the narrow passages would result in heavy casualties, Allied forces under the command of General Robert L. Eichelberger took extreme measures.

They poured approximately 850 gallons of gasoline into the cave's ventilation shafts and fired fuel drums and phosphorus grenades. A massive explosion occurred, igniting a large fire inside the cave that lasted for several days. It is estimated that around 3,000 Japanese soldiers were burned to death or suffocated due to lack of oxygen inside Abyab Binsari. This event marked the end of organized Japanese resistance in Biak and became one of the greatest humanitarian tragedies in the Pacific theater.

Related Figures and Archaeological Remains

The central figure associated with this site is Colonel Naoyuki Kuzume, commander of the Japanese 222nd Infantry Regiment. Although he did not die inside the cave (he performed seppuku, or honorable suicide, at another location in Biak after the defeat), his order to make the cave the last line of defense changed the fate of his thousands of soldiers.

To this day, visitors can still see remnants of authentic war relics inside and around the cave, such as:

• Bullet casings and remnants of machine guns.
• Rusted mess kits, drink bottles, and steel helmets.
• Wrecked military vehicles and aircraft parts collected in a small museum area in front of the cave entrance.
• Soldier remains discovered during site cleaning in the past.

Preservation Status and Restoration

Currently, Gua Jepang (Abyab Binsari) is managed as a cultural heritage site by the Biak Numfor Regency Government. Restoration efforts have been undertaken, particularly on the access road, the stairs leading to the cave floor, and static lighting in the main passage. A memorial monument has also been erected to honor the war victims.

The Japanese government, through its veterans' foundations, regularly visits the site to conduct memorial ceremonies and collect skeletal remains of soldiers through a bone repatriation program agreed upon by the Indonesian and Japanese governments.

Cultural and Educational Value

For the local Biak community, Gua Abyab Binsari holds high sacred and historical value. The cave serves as a reminder of difficult times when local residents were forced into labor (romusha) to strengthen Japanese defenses. Educationally, this site functions as a living history laboratory for younger generations to understand the destructive impact of warfare and the importance of global peace.

Mystically, some local residents still believe in the presence of spiritual energy within the cave, given the many lives tragically lost there. This adds a dimension of cultural depth to the site, where military history intersects with local beliefs.

Conclusion

Gua Jepang (Abyab Binsari) is more than just a dark tourism destination. It is a silent monument that encapsulates military tactical genius, human suffering, and the resilience of nature. Standing at the cold cave floor while gazing towards the light opening in the ceiling, visitors are invited to reflect on the long history that shaped Biak's identity as the "Coral City," which once served as a crucial pivot in determining the course of world history in the 20th century.