Toamasina city is the 1st national port of the country. At the end of RN2, it is reachable after a day from Antananarivo, an 8h windy road.
Almost a must to stop after half day drive at Andasibe village. The Andasibe national park is one of the most visited park in Madagascar. It is a rich rainforest with a lot of endemic species. Better to have at least 2 night here in order to have time for a night walk, day visit of the national park and different small reserves.
Further East, after another half day drive from Andasibe, check the Pangalane Canal. It is an artificial canal which lies along the East coast for more than 600km long and only few metres from the Indian Ocean. Part of it is reachable from some small village like Manambato, Ambila Lemaitso or Akanin'ny Nofy. The Canal, very calm in general except when crossing big lakes offers view on fishermen village, birds, reptiles... The most attractive tour is concentrated on a 1 or two days navigation from Manambato to Toamasina