The Government is giving Stewart Island $5.6 million to help it upgrade infrastructure after the Rakiura National Park was established in 2002.

Conservation Minister Chris Carter said upgrades were needed as more people visited the island because of the park.

The Department of Conservation would fund Southland District Council $2.5 million for key infrastructure projects related to tourism and the national park, he said. A further $3.1 million would be available for work on the island's sewerage system.

"This funding is an investment in the future of Stewart Island and the future of Rakiura National Park, one of New Zealand's most spectacular natural areas, and a paradise for trampers," Mr Carter said.

Rakiura makes up 93 per cent of the area of Stewart Island and Mr Carter was concerned visitors' experience could be undermined if basic infrastructure was not provided or maintained.

"Stewart Island is a small community of just 400 residents. The costs of infrastructure are high because materials, machinery and labour all need to be shipped to the island.

"This funding recognises those problems in the same way the Government has also done for the Chatham Islands."