Aim: In addition to presenting a huge substernal goiter (SSG) reaching the diaphragm, we discuss the diagnosis and treatment of SSGs and bilateral benign multinodular goiters. Background: The presentation of an SSG is usually related to compression of neighboring organs producing symptoms like dyspnoea, dysphonia, and dysphagia. Between 2 to 19% of all goiters are substernal depending on definition. Case description: In the present study we discuss a truly unique case of a huge SSG reaching the diaphragm in a 55-year-old woman. Despite the extension of the goiter, the patient was symptom-free. The patient had a history of subtotal thyroidectomy and radioiodine treatment. The SSG was removed surgically and was characterized as a multinodular goiter on pathological examination. Conclusion: To the best of our knowledge the size, extension, and presentation of the SSG described in this case report is of unprecedented nature. Clinical significance: There is an ongoing discussion about the management of benign bilateral multinodular goiters. With subtotal resection, the risk of nerve injury and hypoparathyroidism decreases, whereas the risk of recurrent disease increases. The present case is an extreme example of recurrent disease but highly relevant when discussing the management of benign bilateral multinodular goiters.