Report says more investment is needed.
Greece and the Greek Islands should be aiming to welcome 24 million holiday tourists by 2021 says a report to the Greek government.
A report on the country's tourism strategic planning says that such as rise in tourist numbers could generate more than €18 billion annually into the struggling Greek economy.
But the report from the Association of Greek Tourism Enterprises (SETE) says around €3 billion needs to be pumped into supporting Greek tourism initiatives each year over the same period.
The investment is needed to improve the country's tourist infrastructure by building more hotels and marinas and in promoting new kinds of tourism.
It would also need a big push to extend Greece's tourism season and especially increasing the number of holiday hotel beds with at least 130,000 more needed on top of the 770,000 holiday beds now available.
The report sets out six key products that make Greece and the Greek Islands such a popular summer holiday destination and that could be improved.
They are Greek Islands sun and beach holidays, city breaks, cultural tourism, nautical tourism, conference facilities and medical tourism.
SETE said that, based on the report, tourism contribution to the country's wealth could reach €44 billion and create some 300,000 direct and indirect jobs.
Sun and beach holidays could be expanded by boosting hotel capacity, especially that aimed at higher accommodation categories and the creation of 'themeed1 holidays with unique selling points.
City break holidays could be promoted much more than they are with breaks in Athens and Thessaloniki forming the focus and the development of thematic walks, launch of 'city cards'
The government should also pump cash into targeted promotions at international associations and a coordinated and simplified bidding process for conferences.
It could also step up cultural tourism with better infrastructure and services in key heritage sites as well as the development of museum features such as the introduction of digital services.
Nautical tourism has opportunities for growth with more cruise ships using Greek ports and the upgrading of marinas to accommodate higher class boats and offering round the clock services
Medical tourism is also a big potential growth area with many health spas in the islands as well as the natural advantages of fresh air and sunshine.
The report says Greece should develop a strategy for each of the country's key tourism products that include appropriate marketing techniques, infrastructure development and promotional strategies.