When driving along the National Route 1A, after passing Ninh Binh City, you will encounter one of the most spectacular sights in Vietnam – Tam Coc (means Three Grottos). Hiring a boat and it will take your through an extensive network of waterways between imposing limestone cliffs erecting from the flat rice paddies. Although the scene still cannot match Halong Bay in terms of size and the number of limestone mountains, Tam Coc is more accessible and less touristy. As the name might suggest, you will undergo three low and dark caves, another reminiscence to Halong Bay. During the trip, you can also have the chance to visit Bich Dong Temple (free entrance) which provides incredible views of the surroundings.
Trang An is another nearby attractions that is quite similar to Tam Coc. Although TrangAn has more caves to pass through, it is more crowded, especially in high season.