Mallapuram is a hilly terraced region. The innumerable streams that wander these hills reach the coconut fringed and picturesque seacoast. In many places, these streams are linked with backwaters, which facilitate a network of inland waterways. The midland region is fertile with thick coconut groves. These are the source of innumerable streams and rivers.

The names and height of some of the hills are as follows:
Vavil or Vayutmala is 2339.73 m, Vellarimala is 2335.58 m, Chakkumala hills are 600.46 m, Urothmala is 477.60 m and Pandalur hills are 610.20 m.

Important rivers:
There are some important rivers that flow through the Mallapuram district. These are as follows:

Chaliyar or Beypore River: Chaliyar or Beyore River is one of the major rivers of the State, which takes its origin from Elembileri hills of Waynad taluk.

Kadalundi River: Kadalundi River is also known as Karimpuzha or Oravanpurampuzha River. It originates from the Silent Valley reserve forests at an elevation of 1219 metres above the sea level. This river forms a part of the west coast navigation system from Palathigal in the south to Mannur in the north. It has a length of 130 metres with a catchment area of 1114 sq. km.

Purapparamba River: Purapparamba is a small river whose length is 8 Km. It originates from the tail end of Purapparamba scratch. It flows in the western direction and crosses the Madras - Mangalore railway line between Tanur and Parappanangadi station. This river is connected with other rivers in the districts by canoli canal.

Tirur River: Tirur River whose length is 48 Km. raises from the Athvanad village of Tirur taluk, flows South-west up to Thiruvnavaya and flows upto Elamkulam in the north western direction. Then it turns southwest and finally joins Bharathapuzha to reach the sea near Ponnani. This river is navigable and motorboat can play between Tirur and Ponnani. It also forms part of west coast water transport system.

Bharathapuzha: Bharathapuzha is also known as Nila nadi or Ponnani River. It has its source in the Anamalai hills at about 982 metres above the main sea level. After flowing through Pollachi taluk of Coimbatore District, it enters the Palakkad district of Kerala state. During its course, it forms the boundary between Palakkad and Trissur Districts.

Sea - Coast: Sea - Coast of the district extends to 70 Km with a minor port at Ponnani. The Port is tidal since it is very shallow; most of the vessels have to be anchored out in the sea. There is large number of fishing centers on this coastline.

Backwater and Canals: There are no major backwaters in this district. The Veliyancode Lake, which is situated at 5 km, South-east of Ponnani, opens to the sea at Veliyancode. A regulator is installed there to prevent the influence of salt water in to the lake. Some of the other minor backwaters of ponnani taluk can be mentioned as Maniyar kayal, Valancherry Kayal and Maravancherry kayal.