In the wake of increasing migrant deaths in the Mediterranean, non-governmental organizations took to the seas to conduct search and rescue operations in 2014. In 2016, this humanitarian fleet rescued 50,000 people in the Central Mediterranean Sea. In the meantime, local solidarity initiatives emerged across Europe, motivated by the arrival of many people in their cities and by deaths and border spectacles in the Mediterranean. Juxtaposing solidarity work in the Mediterranean Sea with solidarity work within the European Union's borders, we examine how the spaces they operate in shape the possibilities and limits of solidarity activism. Despite identifying important differences, we ultimately demonstrate how the solidarity work within Europe and in the Mediterranean Sea fold into each other in complex ways. Moreover, we show how across Europe, people engage in transgressive solidarity work that challenges EU border practices and concomitant categories to reimagine a more welcoming Europe.