India, at the heart of the vast region, has long been its most powerful economic and military force. Still, China has made significant inroads with its much larger financial resources, signing infrastructure deals and securing access to ports in countries surrounding India.

The Maldives’ location makes it a strategic priority for both of Asia’s superpowers. China needs a military presence on the Arabian Sea to safeguard its access to oil from the Persian Gulf. And India, which has been clashing with China along their Himalayan border, wants to make sure that the Maldives, its island neighbor, doesn’t become too cozy with Beijing.

In January, India found itself in a sudden blowup with the Maldives over a perceived threat to the islands’ tourism lifeblood. But the great-power competition across the Maldives’ sky-blue lagoons has yet to reach a boil. Gains and losses are marked more by the tilts of the Maldives’ own politicians — more pro-India at some points, more pro-China at others — and, most of all, by the money that both sides spend to win Maldivian hearts and minds.

From his high-rise office looking out over Malé’s marina, Mohamed Saeed, the Maldives’ minister of economic development and trade, puts his country’s needs in stark terms. Its economy is now worth about $6.5 billion a year, of which $6 billion is earned by tourism, and most of the rest by fishing tuna. The goal is to make it a $12 billion economy within the next five years.

The Maldives discovered tourist dollars in 1972, and it now draws more than a million visitors a year to the “water villas” that branch out from wooden boardwalks and define its high-end resorts.

The country became a democracy only in 2008, with the election of a charismatic young leader, Mohamed Nasheed. The current president, Mohamed Muizzu, was elected five months ago, in the latest swing of the pendulum between India and China. Mr. Muizzu took office after campaigning on an “India Out” platform, which called for expelling about 80 Indian military personnel stationed across the Maldives to provide support.

Mr. Saeed, a Muizzu appointee, was also a cabinet minister during the last “pro-China” government, when the China-Maldives Friendship Bridge was opened. He oversaw a free-trade agreement with China. But these days he sticks to the line that Mr. Muizzu’s government is pursuing only a “pro-Maldives” policy.

There is no preference for China, he says — “we extend our invitation of free trade to all countries,” because “we would like to get the best value for our tuna.”

Pursuing cordial relations with China and India simultaneously might seem the wisest course. But that became more difficult, said Mimrah Ghafoor, a writer and former career diplomat, as both countries stepped up their influence campaigns just as the Maldives was making its transition to democracy.

China has the deeper pockets, with development banks that dwarf India’s. But, Mr. Ghafoor noted, if China “has mostly carrots,” India “has both carrots and the stick.” That is because the Maldives depends on its near neighbor in times of intense need.

Mr. Ghafoor rattled off a list of crises in which Indian help proved indispensable, from fighting back a coup launched from Sri Lanka in 1988 to rescue work after the tsunami of 2004 to a delivery of 1,200 tons of freshwater by airplane and tanker during a shortage in 2014 — a time when the Maldives was led by a China-leaning president.

Beyond money and geography, there is another important difference between India and China as competitors, one that was illustrated during the Maldives’ flare-up with India earlier this year.

Three junior ministers attacked India’s prime minister, Narendra Modi, on social media after he had promoted his country’s own paradisal atoll, an even smaller and far less developed archipelago called Lakshadweep. These “India Out” Maldivians inferred a threat to their economy. In the much louder backlash, nationalistic Indians urged a boycott of the islands.

The disruption to relations offered a contrast with China, which exerts supreme message control. That gives it the ability to negotiate effectively with smaller countries behind closed doors. Beijing may be less comfortable with the Maldives’ new democracy than New Delhi is, but it has navigated relations just as adeptly.

One fierce democracy advocate, Eva Abdulla, a high-ranking member of Parliament, is proudly pro-India. But mostly she is anti-oscillation.

“Flip-flopping on foreign policy is clearly not good for us,” she said. Not in terms of security, and “it doesn’t allow for any kind of stability in development projects.”

Ms. Abdulla, a cousin of Mr. Nasheed, the former president, argues that there are many reasons to stand by India as a partner. She mentions their cultural affinities, as South Asian democracies. Along with hospitals and schools on the far-flung islands, India funds things like a cultural center in Malé, to promote yoga and Indian dance.

Mr. Modi’s pro-Hindu policies at home rub many the wrong way in the Maldives, which is supposedly a 100 percent Muslim society. Even so, “we can’t afford a fistfight with India,” Ms. Abdulla said. On this, she and the president, Mr. Muizzu, whose parties will be battling each other in parliamentary elections in April, agree.

Mr. Muizzu has stepped up his calls for a generic Maldivian nationalism, in favor of the islands’ own language and its Islamic values, while steering clear of an anti-India tone. He has reluctantly made good on his promise to expel the Indian military personnel, but India has not quit its development projects.

One of the most visible is a giant expansion of an airport on the island of Hanimaadhoo, an hour’s flight north from Malé. It is home to one of the planes used by the Indian airmen. And it is the kind of project that makes some Maldivians fear that their sovereign territory is being prepared as a potential battleground in somebody else’s war.

Hanimaadhoo, population 2,664, hardly seems to need the extra runways being built by an Indian firm. Nor do the little-touristed islands nearby. Yet digging machines are at work 24 hours a day, in effect re-engineering the delicate island to make it capable of landing enormous aircraft. A similar airport, built by Indians at the opposite end of the country, makes Hanimaadhoo seem like part of a pattern.

Maldivians are not the only ones to think that. An Indian laborer at the site named Ranjit said he thought it was obvious why India needed to build a military-ready facility here. “China is coming,” he said. “Don’t you see the Chinese ships getting ready?”