Indonesian offshore and coastal areas are vulnerable to swells from Roaring Forties and cyclone disasters. However, the understanding of the characteristics and propagation mechanisms of local disastrous waves is insufficient, posing a threat to the construction, maintenance, and protection of coastal structures. This study establishes a multiple nested wave model based on the third-generation wave model WAVEWATCH Ⅲ. This model includes sole forcing of Roaring Forties and combined forcing of Roaring Forties and cyclone Ernie to simulate the influence of disastrous waves under the Roaring Forties and tropical cyclones in the Indonesian offshore zone and coasts. The following results are obtained. The Indonesian offshore is prevailed by relatively stable southern to southwestern dominant swells and small wind waves under the impacts of the Roaring Forties without cyclone winds. Long propagating swells originated from the Roaring Forties dominate in nearshore coastal waters with deformed directions and strength because of the shoaling effect.