The Marabar Caves are of crucial importance to the story told in A Passage to India because it is through an invitation to the caves that Aziz attempts to make friends with a group of English people. Aziz is Muslim, and his mission is to bridge the cultural divide between the two groups.

Another reason for the caves' huge significance is the fact that it is in the caves that Miss Quested alleges that Aziz made a sexual advance on her. Aziz is arrested on these trumped-up charges, and the British community is filled with what they believe is righteous indignation. The good work that Aziz has been attempting to do in sowing understanding and harmony between the two groups is thus dealt a devastating blow by the trip to the Marabar Caves.

It is this incident—the trip to the Marabar Caves and the alleged sexual assault of Miss Quested—that commands most of the action in the second section. Although Miss Quested eventually tells her fiancé that Aziz actually didn't do anything untoward in the cave, he refuses to do anything about it, and it is only when she takes the stand in Aziz's trial that the truth comes out.

That trip to the Marabar Caves would go on to define Aziz's life in many ways and ultimately forms part of the reason why his friendship with Fielding proves unable to last.

The Marabar Caves are an almost constant, brooding presence in A Passage to India. Even when they form no part of the action, they're still there, lurking in the background. They're just like the stars: always there but not always visible.

On one level, the Marabar Caves' significance lies in their being a manifestation of the Hindu belief that there is a fundamental oneness or unity behind all appearances in the phenomenal world. The caves are dark, deep, mysterious, and unfathomable to all but a few—just like the cosmic unity of the whole universe, which requires many years of study and contemplation to grasp properly.

On the surface, there are numerous cultural differences between the British and Indian characters depicted in the story. But underneath, they are united by their participation in the same underlying reality. But because they lack wisdom and insight, they are unable to realize this.

It's notable, to this end, that when both Adela and Mrs. Moore experience something fearful in the caves, they are unable to make sense of what they have seen. So unnerved are they by the massive, gaping void at the heart of everyday existence revealed by the caves' dark interior that when they emerge blinking into the sunlight, their lives have been changed forever. They have come face to face with the basic reality of the human condition yet are unable to make sense of it. Like everyone else in the story, and indeed like most people throughout the world, they remain trapped in the prison of the phenomenal world, the world of space, time, and objects.

The Marabar Caves are one of the central locations in E. M. Forster's A Passage to India. Indeed, the second section of the novel, "The Caves," is named in reference to them. In this section, Dr. Aziz, a Muslim Indian Man, invites a party of British colonizers he is attempting to befriend on a tour through the caves, which are described as labyrinthine and extremely echo-y. Among the party is Miss Adela Quested, who, when Aziz briefly leaves her alone, falls down a hill. Later she accuses Aziz of attacking/sexually assaulting her (euphemistically referred to as an "insult" by the characters) and claims this caused her fall. This accusation brings simmering racial tensions to the surface as Aziz is arrested and denied bail.

The caves themselves reflect back the ambiguous and sinister nature of these plot developments. The otherness of the landscape and the distortion caused by the echo serve as a mirror to the characters' experiences.

On a simple level, the Marabar Caves are the setting of the crucial event in A Passage to India: Adela's accusation that Dr. Aziz has sexually assaulted her. Adela's charge against Aziz makes racial tensions hidden under the hypocritical coat of respectability of imperial institutions come out in the open. In the trial that follows, the characters' allegiances are severely tested. Yet, on a more complex level, the Marabar Caves are not a mere setting, but have symbolic overtones. With their echo, they can be taken as a symbol of distortion. It is in the Marabar Caves that Adela distorts reality; it is their echo that makes Mrs. Moore aware that her image of India and the image of the Empire is a distorted one. The caves are also a symbol of the unconscious in the human psyche, as they release in Adela all her repressed fears.